Vulnerability in Systerel S2opc

CVE-2026-18257

Improper validity period check for root issuer certificate in CycloneCrypto cryptographic wrapper of S2OPC allows a certificate issued by this root issuer to be considered trusted

Vulnerability class: Improper Certificate Validation

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: 0.002 (4.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 4.5% 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-2026-18257: held from 0.002 to 0.002.

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

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-18257?
CVE-2026-18257 is a medium-severity vulnerability in Systerel S2opc, classified under Improper Certificate Validation. CVSS score: 5.6/10. Published 2026-07-29.
How severe is CVE-2026-18257?
Medium severity. CVSS v3 base score is 5.6 out of 10.