CVE-2026-27138

Panic in name constraint checking for malformed certificates in crypto/x509

State: Published
Severity: 5.9 Medium
Published: Mar 6, 2026
Updated: Mar 10, 2026
Reserved: Feb 17, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	5.9 Medium	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H	CISA-ADP

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
crypto/x509Go standard library	1.26.0-0 to before 1.26.1Affected

References

https://groups.google.com/g/golang-announce/c/EdhZqrQ98hk
https://go.dev/issue/77953
https://go.dev/cl/752183
https://pkg.go.dev/vuln/GO-2026-4600

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