What is CVE-2026-27138?

CVE-2026-27138 is a medium-severity vulnerability in Golang Go, classified under Improper Certificate Validation. CVSS score: 5.9/10. Published 2026-03-06.

How severe is CVE-2026-27138?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Golang Go

CVE-2026-27138

Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS.

Vulnerability class: Improper Certificate Validation

EPSS: 0.004 (27.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Golang Go — versions 1.26.0
Go Standard Library Crypto/x509 — versions 1.26.0-0

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

References

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

Frequently asked questions

What is CVE-2026-27138?: CVE-2026-27138 is a medium-severity vulnerability in Golang Go, classified under Improper Certificate Validation. CVSS score: 5.9/10. Published 2026-03-06.
How severe is CVE-2026-27138?: Medium severity. CVSS v3 base score is 5.9 out of 10.