| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| Issue summary: QUIC server may double free QRX (QUIC record layer RX) object
when channel creation fails for initial packet.
Impact summary: Double free leads to heap corruption, which typically results in
termination of QUIC server process, leading to Denial of Service. There is so
far no evidence that this double free is exploitable for remote code execution,
thus it is considered highly improbable.
CWE: CWE-415: Double Free
Description: In order to validate initial packet, OpenSSL QUIC stack default
packet handler (port_default_packet_handler()) creates a so-called QRX object.
If the initial packet validates successfully with QRX object, the default packet
handler proceeds to channel (connection object) creation. The QRX object used
for packet validation is passed to port_bind_channel(), so it becomes part of
the newly created connection. If port_bind_channel() fails, then it also frees
the QRX object. Once port_bind_channel() returns, the port_default_packet_handler()
detects the failure and proceeds to the error branch, where the same QRX object is
freed for the second time.
The failure in port_bind_channel() function can be induced with a relatively
low effort by a malformed (non RFC 9000 compliant) INITIAL packet. If the packet
carries DCID (destination connection ID) which is shorter than 8 bytes, then
port_bind_channel() jumps to the error path after ossl_quic_lcidm_enrol_odcid()
detects that the DCID has invalid length.
FIPS impact: no
The FIPS module is not affected, as the QUIC implementation is outside of
the OpenSSL FIPS module boundary. |
| Issue summary: Receiving a DTLS record for a future epoch while a handshake
is in progress causes OpenSSL to buffer far more memory than the record
itself requires.
Impact summary: A peer can use a small amount of network traffic to make an
OpenSSL DTLS endpoint retain a disproportionately large amount of memory,
which may lead to a Denial of Service.
CWE: CWE-405: Asymmetric Resource Consumption (Amplification)
Description: While a DTLS handshake is in progress, a peer may legitimately
have already moved on to the next epoch (for example, having sent its
ChangeCipherSpec and Finished messages) before the local endpoint has
processed the same transition, typically because of reordering on the
underlying UDP transport. OpenSSL buffers such early records so that they
can be processed once the local endpoint catches up.
Buffering a record currently retains the entire read buffer it arrived in,
which is sized to hold the largest possible DTLS record (around 16
kilobytes), rather than just the bytes that make up the record itself. Up
to 100 such records may be buffered per connection. As a result, a peer
that sends a stream of small forged records claiming to belong to the next
epoch can cause an OpenSSL DTLS endpoint to retain around 1.7 megabytes of
memory, despite sending only a small fraction of that amount of data over
the network.
An attacker therefore gains a memory amplification factor of around 1200,
and can multiply the effect across as many associations as it is able to
open, making this a remote memory exhaustion Denial of Service risk for
DTLS servers. Since the memory retained per connection remains bounded,
and any limit an application already places on the number of concurrent
associations also bounds the total exposure, this issue has been assessed
as Low severity.
FIPS impact: no
No FIPS modules are affected by this issue as the affected code is outside
the OpenSSL FIPS module boundary.
OpenSSL 4.0, 3.6, 3.5, 3.4, 3.0, 1.1.1 and 1.0.2 are vulnerable to this
issue.
OpenSSL 4.0 users should upgrade to OpenSSL 4.0.2.
OpenSSL 3.6 users should upgrade to OpenSSL 3.6.4.
OpenSSL 3.5 users should upgrade to OpenSSL 3.5.8.
OpenSSL 3.4 users should upgrade to OpenSSL 3.4.7.
OpenSSL 3.0 users should upgrade to OpenSSL 3.0.22.
Premium support customers only:
OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zi
OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zr
This issue was reported on 18 May 2026 by Amazon Web Services.
The fix has been developed by Matt Caswell.
-- cut (non-publishing metadata for internal use) --
Reported by: Amazon Web Services
Fixed by: Matt Caswell |
| Issue summary: OpenSSL CMS decryption sizes the key-unwrap output buffer based
on querying the unwrapped key size, but the AES-WRAP-PAD unwrap primitive
can write and cleanse more bytes than that query reports, causing an 8-byte
out-of-bounds heap write.
Impact summary: An attacker who supplies a crafted CMS message can trigger a
deterministic 8-byte out-of-bounds heap write when the victim decrypts it
with CMS_decrypt(), corrupting the heap and typically resulting in a Denial
of Service.
CWE: CWE-787: Out-of-bounds Write
Description: The key-wrap OID is potentially attacker-controlled on the wire.
CMS unwrapping allows both id-aesNNN-wrap-pad and id-aesNNN-wrap ciphers.
An attacker can take a legitimate message and change a single OID byte to
select the padded variant while leaving the message otherwise valid. Since
the unwrap key is derived from the recipient's private operation (ECDH key
agreement or ML-KEM decapsulation), the RFC 5649 integrity check cannot
pass, and the decryption fails with integrity failure.
The write is a fixed-size (8-byte), fixed-value (zero) heap overflow
immediately past the allocation, requires no special configuration, and is
reachable from the public CMS_decrypt() function. The consequence is
a heap corruption leading to a Denial of Service. The fix in the CMS code
sizes the unwrap output buffer for the worst case so a failed unwrap cannot
write past the allocation.
FIPS impact: no
As the CMS code lives outside the FIPS module boundary, no FIPS
modules are affected by this CVE. |
| Issue summary: The OpenSSL Certificate Management Protocol (CMP) caches
additional certificates (extraCerts) sent in a CMP message, but never expunges
them (for instance if they are invalid). If a server reuses an OSSL_CMP_CTX
frequently, this cache of extraCerts may grow unboundedly, and a malicious
client may flood a CMP server with requests driving this growth.
Impact summary: Users utilizing a CMP server that reuses a single OSSL_CMP_CTX
for the lifetime of a server process may observe unbounded memory growth in the
event a malicious client repeatedly sends requests containing unique extra
certificates, which may lead to OOM conditions.
CWE: CWE-770: Allocation of Resources Without Limits or Throttling
Description: If a remote user sends CMP messages to a server with a list of
extraCerts and the message is rejected, the extraCerts from the message remains
in the server contexts untrusted certificate stack. This exposes servers with
long lived ctx objects to Denial of Service attacks in which an attacker sends
messages intending to be rejected with a large list of additional certificates
repeatedly, forcing the server to store them indefinitely.
The issue was fixed by removing the added extra certs if the message is
rejected, using the same method as when the context is configured to not do
caching at all.
FIPS impact: no
As the CMP code lives outside the FIPS module boundary, no FIPS
modules are affected by this CVE. |
| Issue summary: When OpenSSL processes QUIC traffic from a peer that repeatedly
sends ack-eliciting packets while not acknowledging ACK-only responses, the
QUIC stack can retain ACK-only packet metadata for the lifetime of the
connection.
Impact summary: A remote peer that can complete a QUIC handshake can
cause connection-scoped memory growth which may lead to Denial of Service
through memory exhaustion, especially with sustained traffic or many concurrent
QUIC connections.
CWE: CWE-770: Allocation of Resources Without Limits or Throttling
Description: When the OpenSSL QUIC stack sends an ACK-only packet,
there is no requirement by the QUIC protocol that the peer will acknowledge
that ACK-only packet (i.e. it is itself not ack-eliciting). However, the OpenSSL
implementation stores the metadata about the ACK frames regardless.
In and of itself that's ok, but if a malicious peer establishes a connection, and
then drives the connection such that ACK-only packets are forced from the
OpenSSL implementation peer (i.e., by sending numerous PING frames),
and then withholding any subsequent acks for ack-eliciting data, like
legitimate data, said malicious peer can force inappropriate memory growth
on the OpenSSL peer, potentially leading to a Denial of Service.
The fix is to ensure that we account for the transmission of the ACK-only
packet in the packet histories high and low watermark without actually storing
the ACK-only packet metadata itself.
FIPS impact: no
The OpenSSL FIPS module is not affected as the QUIC code is
outside the FIPS module boundary. |
| Issue summary: OpenSSL CMP password based protection verification only
checks whether the protectionAlg parameter was not NULL and not its
ASN.1 type, before treating it as a PBMParameter. A crafted message can
contain a parameter of a different type, which is then dereferenced as an
invalid pointer.
Impact summary: A remote, unauthenticated attacker can crash an application
acting as a CMP server that accepts PBM-protected messages, or a CMP client
talking to a malicious or intercepted CMP server, resulting in a Denial of
Service.
CWE: CWE-476: NULL Pointer Dereference
Description: When verifying the password-based MAC protection of a CMP
message, OpenSSL library reads the protectionAlg algorithm parameter with
X509_ALGOR_get0(), which returns both the parameter type and its value
pointer. The value is then cast to an ASN1_STRING and treated as the
expected PBMParameter after only checking that pointer is not NULL. The
parameter type returned by X509_ALGOR_get0() was never consulted.
This happens during protection verification, before any MAC is computed, so
no knowledge of the PBM shared secret is required; the only precondition is
that PBM verification is reachable. On the server side this is reached from
OSSL_CMP_SRV_process_request() for any application that stands up a CMP
server accepting PBM-protected messages, and on the client side from CMP
response validation against a malicious or on-path (MITM) server. The
reliable consequence is a denial of service; there is no memory disclosure,
no controlled memory write, and no path to code execution. CMP is a
specialized feature that an application must explicitly enable.
FIPS impact: no
As the CMP code lives outside the FIPS module boundary, no FIPS modules
are affected by this CVE. |
| Issue summary: In a server or client configuration with RFC7250 Raw Public Keys (RPKs)
enabled, and only the private key (with no associated certificate) configured locally,
a NULL pointer dereference may occur when the remote peer solicits raw public keys and
also sends the typically omitted "signature_algorithms_cert" TLS extension.
Impact summary: The impact is limited to a possible Denial of Service as a result of
an application abort, no data disclosure or remote command execution are possible.
CWE: CWE-476: NULL Pointer Dereference
Description: While a passing comment in sample code in the documentation suggests
that key-only RPK configurations are supported, the best-practice RPK configuration
is to always configure a corresponding certificate (possibly self-signed or
signed by any convenient CA).
When the private key is configured along with a matching certificate, the
"signature_algorithms_cert" extension is handled reliably even without the
fix, and peer clients or servers that don't support raw public keys may be
able to complete a TLS connection by pinning or verifying the corresponding
certificate or its public key.
Deployments that prefer to configure just a private key with no certificate
need to upgrade to an updated release as noted below.
FIPS impact: no
No FIPS modules are affected by this issue, as the SSL protocol implementation
is outside the OpenSSL FIPS module boundary. |
| Issue summary: OpenSSL CMP response validation passed an unexpected response
sender distinguished name directly as the format string to `ERR_raise_data()`.
Impact summary: A malicious or intercepted CMP endpoint can crash a CMP client
that enforces an expected sender or uses a pinned server certificate whose
subject becomes the default expected sender.
CWE: CWE-134 (Use of Externally-Controlled Format String)
Description: When validating a received CMP message, ossl_cmp_msg_check_update()
converts the peer-supplied sender distinguished name with X509_NAME_oneline()
and passes it directly as the format argument to ERR_raise_data(). Percent
characters survive the conversion, so a sender DN such as "CN=%s%n" reaches
BIO_vsnprintf() as an attacker-controlled format string with no matching variadic
arguments. This path is only reached when the caller configures an expected
sender or pins a server certificate, which is the normal configuration for a
CMP client validating server responses.
Since the attacker controls the format string but none of the variadic
arguments, such specifiers as %s and %n dereference or write through unrelated
stack contents and crash the client. The reliable consequence is a denial of
service, when the response comes from a malicious or intercepted CMP endpoint.
There is no controlled memory write, arbitrary-address read, or reliable path
to remote code execution.
FIPS impact: no
No FIPS modules are affected by this issue, as the CMP protocol
implementation is outside the OpenSSL FIPS module boundary. |
| Issue summary: ChaCha20-Poly1305 and AES-OCB decryption with an empty
ciphertext can report success without verifying the supplied authentication
tag when the operation is finalized by calling the EVP_Cipher() function.
Impact summary: Applications calling EVP_Cipher() on an empty ciphertext and
expecting the call to check the AEAD tag may accept forged messages.
CWE: CWE-354 (Improper Validation of Integrity Check Value)
Description: The EVP_Cipher() API call for AEAD ciphers behaves like a one
shot encryption and decryption call. It also verifies the AEAD tag after the
decryption operation. However for AES-OCB and ChaCha20-Poly1305 ciphers
it skipped the AEAD tag verification when an empty ciphertext was passed to
the function. The callers of this function might believe that a successful
return indicates a valid AEAD tag for these ciphers, even when that has not
truly been validated in this case.
FIPS impact: no
The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this CVE
as the affected algorithms are not FIPS approved and thus not implemented
in the FIPS module. |
| Issue summary: A specially crafted PKCS#7 or S/MIME signed message could
trigger a use-after-free during PKCS#7 signature verification.
Impact summary: A use-after-free may result in process crashes, heap
corruption, or potentially remote code execution.
When processing a PKCS#7 or S/MIME signed message, if the SignedData
digestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may
incorrectly free a caller-owned BIO during PKCS7_verify(). A subsequent
use of the BIO by the calling application results in a use-after-free
condition.
In the common case this occurs when the application later calls
BIO_free() on the BIO originally passed to PKCS7_verify(). Depending
on allocator behavior and application-specific BIO usage patterns, this
may result in a crash or other memory corruption. In some application
contexts this may potentially be exploitable for remote code execution.
Applications that process PKCS#7 or S/MIME signed messages using OpenSSL
PKCS#7 APIs may be affected. Applications using the CMS APIs for this
processing are not affected.
The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this
issue, as the affected code is outside the OpenSSL FIPS module boundary. |
| Issue summary: When an OpenSSL QUIC server (Listener SSL object) processes
valid QUIC Initial packets for unknown destination connection IDs, it
can allocate and queue new incoming channels without enforcing any limit.
Impact summary: A remote peer that can make many Initial packets reach the
server listener faster than the application accepts connections, can cause the
memory allocated to store the per-channel state to grow without any limits,
potentially making the QUIC listener unavailable and causing Denial of Service.
CWE: CWE-770: Allocation of Resources Without Limits or Throttling
Description: The function that handles inbound QUIC packets uses
Connection-Id from the packet header to find an existing connection
(QUIC channel). If no existing connection is found and the packet
type is INITIAL, the function treats the packet as a new connection. It
allocates a new channel object and inserts it into a queue where it
waits to be accepted by the local application with SSL_accept(3ossl).
The memory occupied by these initial channel objects may grow
without bounds if the application is not able to call SSL_accept()
frequently enough to serve these inbound connection requests.
The issue is present since OpenSSL 3.5 when the QUIC server implementation
was added.
The fix introduces a limit for pending connections. The default limit is set
to 256 pending connections (waiting to be accepted by the local application).
Applications may change the default by calling SSL_set_value_uint(3ossl).
FIPS impact: no
The FIPS module is not affected as the QUIC implementation is outside of
the OpenSSL FIPS module boundary. |
| Issue summary: A malicious TLS server can cause a memory leak in a TLS
client that has enabled OCSP response checking by sending an OCSP
response that contains no single response entries.
Impact summary: An attacker can leak an attacker-tunable amount of memory
per TLS handshake in a victim client application. A long-running client
that repeatedly connects to a malicious server can have its memory
exhausted, resulting in a Denial of Service.
CWE: CWE-401: Missing Release of Memory after Effective Lifetime
Description: The affected function is called during X.509 certificate
chain verification when OCSP response checking is enabled
with the X509_V_FLAG_OCSP_RESP_CHECK or X509_V_FLAG_OCSP_RESP_CHECK_ALL
verification flags, for example when a TLS client verifies an OCSP
response stapled into the TLS handshake by the server.
When the received BasicOCSPResponse contains an empty SEQUENCE OF
SingleResponse, which is permitted on the wire and accepted by the
OpenSSL decoder, the OCSP_BASICRESP structure allocated by
OCSP_response_get1_basic() was not freed because an early return
bypassed the cleanup code at the end of the function.
The amount of memory leaked per handshake can be amplified by the
attacker by padding the certs field of the BasicOCSPResponse with
bogus certificates, which are parsed and stored in the leaked
structure before the empty response check triggers the early return.
A long-running TLS client that repeatedly connects to a malicious
server can have its memory exhausted over time.
OCSP response checking is not enabled by default. Only client
applications that explicitly enable the OCSP response check
verification flags are affected.
FIPS impact: no
The FIPS modules in 4.0 and 3.6 are not affected by this issue as the
affected code is outside the OpenSSL FIPS module boundary. |
| Issue summary: When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42)
peer key, the peer key is not properly checked for the subgroup membership.
Impact summary: A malicious peer which presents an X9.42 key carrying the
victim's p and g parameters, a forged q = r (a small prime factor of the
cofactor (p−1)/q_local), and a public value Y of order r can recover the
victim's private key after a small number of key exchange attempts.
When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42) peer key, the
subgroup membership check Y^q ≡ 1 (mod p) is performed using the peer's
own q parameter, not the local key's q. The peer's domain parameters are
then matched against the domain parameters of the private key, but the value
of q is not compared.
A malicious peer who presents an X9.42 key carrying the victim's p, g,
a forged q = r (a small prime factor of the cofactor), and a public
value Y of order r passes all checks. The shared secret then takes only
r distinct values, leaking priv mod r. Repeating for each small-prime
factor of the cofactor and combining via CRT recovers the full private
key (Lim–Lee / small-subgroup-confinement attack).
The realistic attack surface is narrow: principally CMP deployments with
long-lived RA/CA DHX keys and bespoke enterprise or government applications
using X9.42 DHX static keys with interactive protocols and therefore this
issue was assigned Low severity.
The FIPS modules in 4.0, 3.6, 3.5, 3.4, 3.1.2 and 3.0 are affected by this
issue. |
| Issue summary: Applications performing certificate name checks (e.g., TLS
clients checking server certificates) may attempt to read an invalid memory
address resulting in abnormal termination of the application process.
Impact summary: Abnormal termination of an application can a cause a denial of
service.
Applications performing certificate name checks (e.g., TLS clients checking
server certificates) may attempt to read an invalid memory address when
comparing the expected name with an `otherName` subject alternative name of an
X.509 certificate. This may result in an exception that terminates the
application program.
Note that basic certificate chain validation (signatures, dates, ...) is not
affected, the denial of service can occur only when the application also
specifies an expected DNS name, Email address or IP address.
TLS servers rarely solicit client certificates, and even when they do, they
generally don't perform a name check against a reference identifier (expected
identity), but rather extract the presented identity after checking the
certificate chain. So TLS servers are generally not affected and the severity
of the issue is Moderate.
The FIPS modules in 3.3, 3.2, 3.1 and 3.0 are not affected by this issue. |
| Issue summary: When the X509_VERIFY_PARAM_set1_email is called by an
application to validate a crafted e-mail address, such as during S/MIME
message validation, an out of bounds read can happen.
Impact summary: This out of bounds read will not directly exfiltrate
the data read to the attacker so the most likely result is a crash and
a Denial of Service.
An internal helper function called from X509_VERIFY_PARAM_[set|add]_email()
used a wrong length when validating the local part of an email address.
This could cause the 64 octet limit on the local part of an email address
to be not enforced, or cause an out of bound read and potentially a crash.
The bug is reachable via S-MIME validation with a crafted From: address
supplied in an email message that can potentially cause a crash.
No FIPS modules are affected by this issue as the affected code is outside
the OpenSSL FIPS module boundary. |
| Issue summary: An attacker-controlled CMP (Certificate Management Protocol)
server could trigger a NULL pointer dereference in a CMP client application.
Impact summary: A NULL pointer dereference causes a crash of the
application and a Denial of Service.
An attacker controlling a CMP server (or acting as a man-in-the-middle) could
craft a CMP response containing a CRMF (Certificate Request Message Format)
CertRepMessage with an EncryptedValue structure where the symmAlg field
has an algorithm OID but no parameters field. When the OpenSSL CMP client
processes this response, the NULL dereference occurs, causing a crash of
the CMP client.
Applications that process untrusted CMP/CRMF messages may be affected.
The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this
issue, as the affected code is outside the OpenSSL FIPS module boundary. |
| Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to
Bleichenbacher-style attack when an attacker is able to provide the CMS or
S/MIME messages and observe the error code and/or decryption output.
Impact summary: The Bleichenbacher-style attack allows an attacker to use the
victim's vulnerable application as a way to decrypt or sign messages with the
victim's private RSA key.
The attack is possible in 2 variants.
1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without
providing the recipient certificate. In this case OpenSSL iterates over every
KeyTransRecipientInfo (KTRI) without stopping at the first success.
An attacker who authors a message with two KTRI entries — the first one
wrapping a real CEK under the victim's public key, the second with an
arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to
get a valid PKCS#1 v1.5 padding if the error code of the application is
available.
That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an
adaptive-chosen-ciphertext side channel from which the attacker decrypts any
RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under
it.
2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with
the recipient certificate, and the recipient is not found, a random
key is substituted.
An attacker who authors a message and is able to compare both error code and
the result of the decryption, can mount a Bleichenbacher oracle.
We are not aware of any applications that provide a remote attacker
an opportunity to mount an attack described in these scenarios. We consider
the existence of such application very unlikely, and for this reason this
CVE has been evaluated as Low severity.
To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the
invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described
in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit
rejection was explicitly disabled.
The implicit rejection mechanism always returns a plaintext value,
the symmetric key. This result is deterministic for the ciphertext and the
private key. The length of the decryption result can happen to match the
length of the key of the symmetric cipher that was used for the content
encryption. When a certificate is not provided, the last RecipientInfo
producing a key that looks valid will be used. It may cause getting garbage
content on decryption. As a proper way to deal with this a recipient
certificate has to be provided to identify the particular RecipientInfo for
decryption.
The FIPS modules in 4.0, 3.6, 3.5, and 3.4 are not affected by this issue, as
CMS and S/MIME processing happens outside the OpenSSL FIPS module boundary. |
| Issue summary: When an application drives an AES-OCB context through the
public EVP_Cipher() one-shot interface, the application-supplied
initialisation vector (IV) is silently discarded.
Impact summary: Every message encrypted under the same key uses the
same effective nonce regardless of the IV supplied by the caller,
resulting in (key, nonce) reuse and loss of confidentiality. If the
same code path is used to compute the authentication tag, the tag
depends only on the (key, IV) pair and not on the plaintext or
ciphertext, allowing universal forgery of arbitrary ciphertext from a
single captured message.
OpenSSL provides two ways to drive a cipher: the documented streaming
interface (EVP_CipherUpdate / EVP_CipherFinal_ex) and a lower-level
one-shot, EVP_Cipher(), whose documentation explicitly recommends
against use by applications in favour of EVP_CipherUpdate() and
EVP_CipherFinal_ex(). The OCB provider's streaming handler flushes
the application-supplied IV into the OCB context before processing
data; the one-shot handler did not. Every call to EVP_Cipher() on an
AES-OCB context therefore ran with the all-zero key-derived offset
state left by cipher initialisation, regardless of the caller's IV.
If EVP_EncryptFinal_ex() is subsequently used to obtain the
authentication tag, the deferred IV setup runs at that point and
clears the running checksum that should have been accumulated over the
plaintext. The resulting tag is a function of (key, IV) only and
verifies against any ciphertext produced under the same (key, IV)
pair.
The OpenSSL SSL/TLS implementation is not affected: AES-OCB is not a
TLS cipher suite, and libssl does not call EVP_Cipher() in any case.
Applications that drive AES-OCB through the documented streaming AEAD
API (EVP_CipherUpdate / EVP_CipherFinal_ex) are not affected. Only
applications that combine the AES-OCB cipher with the EVP_Cipher()
one-shot API are vulnerable.
The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by
this issue, as AES-OCB is outside the OpenSSL FIPS module boundary. |
| Issue summary: The implementations of AES-SIV (RFC 5297) and AES-GCM-SIV
(RFC 8452) mishandle the authentication of AAD (Additional Authenticated
Data) with an empty ciphertext allowing a forgery of such messages.
Impact summary: An attacker can forge empty messages with arbitrary AAD
to the victim's application using these ciphers.
AES-SIV (RFC 5297) and AES-GCM-SIV (RFC 8452) are nonce-misuse-resistant AEAD
modes: they accept a key, nonce, optional AAD (bytes that are authenticated
but not encrypted), and plaintext, and produces ciphertext plus a 16-byte
tag. On decrypt, `EVP_DecryptFinal_ex()` is documented to return success only
if the tag is verified succesfully.
In OpenSSL's provider implementation of these ciphers, the expected tag is
computed only when decryption function is invoked with non-empty data.
If the caller supplies AAD and then calls `EVP_DecryptFinal_ex()` without
invocation of the ciphertext update, which can happen when the received
ciphertext length is zero, the tag is never recalculated and still holds its
all-zeros value.
When AES-GCM-SIV is used, an attacker who sends arbitrary AAD, empty
ciphertext, and all-zeros tag passes authentication under any key they do not
know, single-shot. When AES-SIV is used, for mounting the attack it's
necessary for the application to reuse the decryption context without
resetting the key.
AES-SIV is implemented since OpenSSL 3.0. AES-GCM-SIV is implemented since
OpenSSL 3.2.
No protocols implemented in OpenSSL itself (TLS/CMS/PKCS7/HPKE/QUIC) support
either AES-GCM-SIV or AES-SIV. To mount an attack, the applications must
implement their own protocol and use the EVP interface. Also they must skip the
ciphertext update when a message with an empty ciphertext arrives.
The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this
issue, as these algorithms are not FIPS approved and the affected code is
outside the OpenSSL FIPS module boundary. |
| Issue summary: A signed integer overflow when sizing the destination
buffer for Unicode output in ASN1_mbstring_ncopy() can lead to a heap
buffer overflow.
Impact summary: A heap buffer overflow may lead to a crash or possibly
attacker controlled code execution or other undefined behaviour.
In ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination
size for Unicode output is computed in a signed int: by left shift
of the input character count for BMPSTRING (UTF-16) and
UNIVERSALSTRING (UTF-32), and by summing per-character byte counts
for UTF8STRING. The calculation overflows when the input reaches
around 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30
characters) the size wraps to zero, OPENSSL_malloc(1) is called, and
the subsequent character copy writes several gigabytes past the
one-byte allocation.
X.509 certificate processing routes through ASN1_STRING_set_by_NID(),
whose DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID
size limits cap the input length; no network protocol or
certificate-handling path in OpenSSL exercises the overflow.
Triggering the bug requires an application that calls
ASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly, or registers
a custom string type via ASN1_STRING_TABLE_add(), with
attacker-controlled input on the order of half a gigabyte or more.
For these reasons this issue was assigned Low severity.
The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by
this issue, as the affected code is outside the OpenSSL FIPS module
boundary. |
