Improper Verification of Cryptographic Signature and Improper Certificate Validation in the OPC UA driver of Apache PLC4X (PLC4J) allows an attacker in a network position between client and server to impersonate the OPC UA server and to read, forge or modify secure-channel traffic, including user credential ssent by the client.
The defect manifests differently depending on the version:
- In 0.9.0 through 0.11.0 a failed message-signature check is only logged and never enforced, and there is no mechanism to verify the server certificate: it is taken from the unauthenticated GetEndpoints discovery response and used to encrypt the user's password.
- In 0.12.0 through 0.13.1 the signature check is inverted (valid signatures are rejected, invalid ones accepted), and server certificates are accepted without a trust anchor by default.
- In all affected versions the default security policy is None. Starting with 0.12.0 the driver additionally continues silently at a weaker security policy than the one configured, and starting with 0.13.0 endpoint selection prefers the weakest matching endpoint.
Users checking only for one of these mechanisms may wrongly conclude they are unaffected.
This issue affects Apache PLC4X: from 0.9.0 before 1.0.0.
Users are recommended to upgrade to version 1.0.0, which fixes the issue. Version 1.0.0 verifies message signatures correctly, refuses to connect unless the server certificate can be verified against a configured trust store or pinned certificate, defaults to Basic256Sha256 with SignAndEncrypt, and fails the
connection if the negotiated security policy is weaker than the configured one.
The defect manifests differently depending on the version:
- In 0.9.0 through 0.11.0 a failed message-signature check is only logged and never enforced, and there is no mechanism to verify the server certificate: it is taken from the unauthenticated GetEndpoints discovery response and used to encrypt the user's password.
- In 0.12.0 through 0.13.1 the signature check is inverted (valid signatures are rejected, invalid ones accepted), and server certificates are accepted without a trust anchor by default.
- In all affected versions the default security policy is None. Starting with 0.12.0 the driver additionally continues silently at a weaker security policy than the one configured, and starting with 0.13.0 endpoint selection prefers the weakest matching endpoint.
Users checking only for one of these mechanisms may wrongly conclude they are unaffected.
This issue affects Apache PLC4X: from 0.9.0 before 1.0.0.
Users are recommended to upgrade to version 1.0.0, which fixes the issue. Version 1.0.0 verifies message signatures correctly, refuses to connect unless the server certificate can be verified against a configured trust store or pinned certificate, defaults to Basic256Sha256 with SignAndEncrypt, and fails the
connection if the negotiated security policy is weaker than the configured one.
Metrics
Affected Vendors & Products
Advisories
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Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Wed, 30 Sep 2026 10:30:00 +0000
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Wed, 30 Sep 2026 09:45:00 +0000
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Apache
Apache plc4x |
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Apache
Apache plc4x |
Wed, 30 Sep 2026 08:00:00 +0000
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| Description | Improper Verification of Cryptographic Signature and Improper Certificate Validation in the OPC UA driver of Apache PLC4X (PLC4J) allows an attacker in a network position between client and server to impersonate the OPC UA server and to read, forge or modify secure-channel traffic, including user credential ssent by the client. The defect manifests differently depending on the version: - In 0.9.0 through 0.11.0 a failed message-signature check is only logged and never enforced, and there is no mechanism to verify the server certificate: it is taken from the unauthenticated GetEndpoints discovery response and used to encrypt the user's password. - In 0.12.0 through 0.13.1 the signature check is inverted (valid signatures are rejected, invalid ones accepted), and server certificates are accepted without a trust anchor by default. - In all affected versions the default security policy is None. Starting with 0.12.0 the driver additionally continues silently at a weaker security policy than the one configured, and starting with 0.13.0 endpoint selection prefers the weakest matching endpoint. Users checking only for one of these mechanisms may wrongly conclude they are unaffected. This issue affects Apache PLC4X: from 0.9.0 before 1.0.0. Users are recommended to upgrade to version 1.0.0, which fixes the issue. Version 1.0.0 verifies message signatures correctly, refuses to connect unless the server certificate can be verified against a configured trust store or pinned certificate, defaults to Basic256Sha256 with SignAndEncrypt, and fails the connection if the negotiated security policy is weaker than the configured one. | |
| Title | Apache PLC4X: OPC UA secure channel: integrity bypass, unverifiable server certificate, and silent downgrade | |
| Weaknesses | CWE-295 CWE-347 CWE-757 |
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| References |
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| Metrics |
cvssV4_0
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Projects
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Status: PUBLISHED
Assigner: apache
Published:
Updated: 2026-09-30T10:08:10.861Z
Reserved: 2026-09-29T11:40:54.414Z
Link: CVE-2026-102508
No data.
Status : Received
Published: 2026-09-30T08:16:31.903
Modified: 2026-09-30T10:17:15.920
Link: CVE-2026-102508
No data.
OpenCVE Enrichment
Updated: 2026-09-30T11:30:18Z