Vulnerability in Systerel S2opc

CVE-2026-6899

Check for certificate revocation only considers the first matching CRL and ignores other valid CRLs of the same CA in the CycloneCrypto cryptographic wrapper of S2OPC library. It might allow connection between an OPC UA client and server using a revoked certificate.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.6 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.001 (1.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 1st percentile — 1.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-6899: held from 0.002 to 0.001.

EPSS over last 30 days · oldest: 0.002 · newest: 0.001 · change: -0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-6899?
CVE-2026-6899 is a medium-severity vulnerability in Systerel S2opc, classified under Improper Check for Certificate Revocation. CVSS score: 5.6/10. Published 2026-06-09.
How severe is CVE-2026-6899?
Medium severity. CVSS v3 base score is 5.6 out of 10.