Quick answers
- Is CVE-2026-6899 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-6899 being exploited in the wild.
- How severe is CVE-2026-6899?
- Medium severity, with a CVSS score of 5.6, published 9 June 2026.
- Which products and versions are affected?
- Systerel S2OPC a442f47200aaf3e58194b209e0738a4f9056393a.
- Is there a fix for CVE-2026-6899?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-6899 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-6899?
- Check whether you run Systerel S2OPC at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is classified as an improper check for certificate revocation (CWE-299) within the `crt_verifycrl_and_check_revocation` function of the S2OPC CycloneCrypto wrapper. The implementation incorrectly terminates its search after finding the first matching CRL for a Certificate Authority, ignoring subsequent valid CRLs that may contain the certificate's revocation status. An attacker using a revoked certificate could successfully establish or maintain an OPC UA connection if the revocation entry exists in a CRL not processed by the library. The issue was identified in commit a442f472 and requires a fix to iterate through all associated CRLs to ensure comprehensive revocation verification.
Affected products
- Systerel S2OPC a442f47200aaf3e58194b209e0738a4f9056393a
Timeline
- 2026-06-09: disclosed
- 2026-06-09: advisory