CVE-2026-27138

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

CVSS 5.9 MEDIUMEPSS 0.4%

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 5.9EPSS 0.4%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

06 Mar 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Go standard library · crypto/x509

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References

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