Net::DNS::DomainName::decode follows RFC 1035 compression pointers by recursing into itself with no depth limit. It is possible to construct a name which saturates the call stack (at least with larger TCP responses), leading to a potential Denial of Service.
The guard `$link < $offset` prevents forward and circular chains, but still allows arbitrarily long backward chains. The per-offset cache (`$cache`) is populated at the start of each call and short-circuits only re-traverses of the same offset - the initial descent through a fresh chain still recurses at full depth.
A crafted packet can chain two-byte compression pointers so that each one points two bytes earlier than the previous, producing a chain length of `offset / 2`. For the 14-bit pointer field (max offset 16383) this gives up to ~8191 recursive frames. For a TCP DNS message the limit is the 16-bit length field (~32767 frames). Perl's default C stack handles only a few thousand frames; beyond that the process receives SIGSEGV or similar, which is a denial-of-service for any application parsing untrusted DNS data.
The vulnerability is triggered by `Net::DNS::Packet->new(\$wire)` i.e. any point where the library decodes a DNS message from the network.
Metrics
Affected Vendors & Products
No data.
No data.
OpenCVE Enrichment is a feature of OpenCVE that uses AI to automatically link vendors and products to CVEs. Learn more on GitHub.
| Vendors | Products |
|---|---|
|
Nlnet Labs
Subscribe
|
Net Dns
Subscribe
|
No advisories yet.
Solution
Upgrade to version 1.56 or later.
Workaround
No workaround given by the vendor.
Tue, 28 Jul 2026 20:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Nlnet Labs
Nlnet Labs net Dns |
|
| Vendors & Products |
Nlnet Labs
Nlnet Labs net Dns |
Tue, 21 Jul 2026 19:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
|
Mon, 20 Jul 2026 18:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Net::DNS versions through 1.55 for Perl allow Denial of Service via deep DNS compression pointer chains. Net::DNS::DomainName::decode follows RFC 1035 compression pointers by recursing into itself with no depth limit. It is possible to construct a name which saturates the call stack (at least with larger TCP responses), leading to a potential Denial of Service. The guard `$link < $offset` prevents forward and circular chains, but still allows arbitrarily long backward chains. The per-offset cache (`$cache`) is populated at the start of each call and short-circuits only re-traverses of the same offset - the initial descent through a fresh chain still recurses at full depth. A crafted packet can chain two-byte compression pointers so that each one points two bytes earlier than the previous, producing a chain length of `offset / 2`. For the 14-bit pointer field (max offset 16383) this gives up to ~8191 recursive frames. For a TCP DNS message the limit is the 16-bit length field (~32767 frames). Perl's default C stack handles only a few thousand frames; beyond that the process receives SIGSEGV or similar, which is a denial-of-service for any application parsing untrusted DNS data. The vulnerability is triggered by `Net::DNS::Packet->new(\$wire)` i.e. any point where the library decodes a DNS message from the network. | |
| Title | Net::DNS versions through 1.55 for Perl allow Denial of Service via deep DNS compression pointer chains | |
| Weaknesses | CWE-674 | |
| References |
|
Projects
Sign in to view the affected projects.
MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-07-21T18:56:01.149Z
Reserved: 2026-07-19T10:13:00.756Z
Link: CVE-2026-64194
Vulnrichment
Updated: 2026-07-20T20:30:05.425Z
NVD
Status : Deferred
Published: 2026-07-20T19:17:30.157
Modified: 2026-07-21T19:35:17.130
Link: CVE-2026-64194
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-08-01T07:15:03Z