What is CVE-2026-42508?

CVE-2026-42508 is a critical-severity vulnerability in Golang Crypto, classified under Improper Certificate Validation. CVSS score: 9.1/10. Published 2026-05-22.

How severe is CVE-2026-42508?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Vulnerability in Golang Crypto

CVE-2026-42508

Previously, a revoked 'SignatureKey' belonging to a CA was not correctly checked for revocation. Now, both the 'key' and 'key.SignatureKey' are checked for @revoked.

Vulnerability class: Improper Certificate Validation

EPSS: 0.000 (11.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Golang Crypto
Golang.org/x/crypto Golang.org/x/crypto/ssh/knownhosts — versions 0

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

References

security@golang.org (Issue Tracking)
security@golang.org (Issue Tracking)
security@golang.org (Mailing List)
security@golang.org (Vendor Advisory)

Frequently asked questions

What is CVE-2026-42508?: CVE-2026-42508 is a critical-severity vulnerability in Golang Crypto, classified under Improper Certificate Validation. CVSS score: 9.1/10. Published 2026-05-22.
How severe is CVE-2026-42508?: Critical severity. CVSS v3 base score is 9.1 out of 10.