Medium 5.9Published Mar 6, 2026

CVE-2026-27138Panic in name constraint checking for malformed certificates in crypto/x509

Updated under an hour ago (Oct 27, 2026, 9:00 AM ET)

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It affects Go standard library crypto/x509 and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Go standard library crypto/x509

Exploited in the last 30 days

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: 5.9 MEDIUM (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-1285
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Go
NVD analysis: Analyzed
Record last updated: Mar 10, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Go standard library crypto/x509 go_standard_library:crypto_x509 (from the name)	from 1.26.0-0 before 1.26.1	CNA record
golang go golang:go	1.26.0	NVD

References

References

https://groups.google.com/g/golang-announce/c/EdhZqrQ98hk	release-notes
https://go.dev/issue/77953	issue-tracking
https://go.dev/cl/752183	mailing-list
https://pkg.go.dev/vuln/GO-2026-4600	vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.