What is CVE-2025-61727?

CVE-2025-61727 is a medium-severity vulnerability in Golang Go, classified under Improper Certificate Validation. CVSS score: 6.5/10. Published 2025-12-03.

How severe is CVE-2025-61727?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Golang Go

CVE-2025-61727

An excluded subdomain constraint in a certificate chain does not restrict the usage of wildcard SANs in the leaf certificate. For example a constraint that excludes the subdomain test.example.com does not prevent a leaf certificate from claiming the SAN *.example.com.

Vulnerability class: Improper Certificate Validation

Published 2025-12-03 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (18.7th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 18.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Golang Go
Go Standard Library Crypto/x509 — versions 0, 1.25.0

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

References

go.dev/cl/723900 (Patch)
go.dev/issue/76442 (Issue Tracking)
groups.google.com/g/golang-announce/c/8FJoBkPddm4 (Mailing List, Release Notes)
pkg.go.dev/vuln/GO-2025-4175 (Vendor Advisory)

Frequently asked questions

What is CVE-2025-61727?: CVE-2025-61727 is a medium-severity vulnerability in Golang Go, classified under Improper Certificate Validation. CVSS score: 6.5/10. Published 2025-12-03.
How severe is CVE-2025-61727?: Medium severity. CVSS v3 base score is 6.5 out of 10.