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

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Summary

CVECVE-2026-27138
StatePUBLISHED
AssignerGo
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-06 22:16:00 UTC
Updated2026-04-21 14:39:28 UTC
DescriptionCertificate 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.

Risk And Classification

Primary CVSS: v3.1 5.9 MEDIUM from ADP

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

EPSS: 0.000210000 probability, percentile 0.058940000 (date 2026-04-21)

Problem Types: CWE-295 | CWE-1285: Improper Validation of Specified Index, Position, or Offset in Input

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Golang Go 1.26.0 All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Go Standard Library Crypto/x509 affected 1.26.0-0 1.26.1 semver Not specified

References

ReferenceSourceLinkTags
pkg.go.dev/vuln/GO-2026-4600 [email protected] pkg.go.dev Vendor Advisory
groups.google.com/g/golang-announce/c/EdhZqrQ98hk [email protected] groups.google.com Release Notes
go.dev/cl/752183 [email protected] go.dev Mailing List
go.dev/issue/77953 [email protected] go.dev Issue Tracking
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Jakub Ciolek (en)

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