Critical 9.2Published Sep 30, 2026

CVE-2026-102508Apache PLC4X: OPC UA secure channel: integrity bypass, unverifiable server certificate, and silent downgrade

Updated under an hour ago (2026-10-19 08:30 UTC)

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It affects Apache Software Foundation Apache PLC4X. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.13%, higher than 3% of scored CVEs.

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Every CVE for Apache Software Foundation Apache PLC4X

Exploited in the last 30 days

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.

CVSS: 9.2 CRITICAL (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness (CWE): CWE-347, CWE-295, CWE-757
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.13% (percentile 3)
Assigned by: apache
NVD analysis: Awaiting Analysis
Record last updated: Sep 30, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Apache Software Foundation Apache PLC4X apache_software_foundation:apache_plc4x (from the name)	from 0.9.0 before 1.0.0; 1.0.0 not affected	CNA record

References

https://lists.apache.org/thread.html/o076mcnsx6wnqpdy780m7s6hddbbnjfwvendor-advisory
http://www.openwall.com/lists/oss-security/2026/09/30/4

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.