Incorrect enforcement of email constraints in crypto/x509

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Summary

CVECVE-2026-27137
StatePUBLISHED
AssignerGo
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-06 22:16:00 UTC
Updated2026-04-21 14:40:31 UTC
DescriptionWhen verifying a certificate chain which contains a certificate containing multiple email address constraints which share common local portions but different domain portions, these constraints will not be properly applied, and only the last constraint will be considered.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

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

EPSS: 0.000130000 probability, percentile 0.022300000 (date 2026-04-21)

Problem Types: CWE-295 | CWE-295: Improper Certificate Validation

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

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

CVSS:3.1/AV:N/AC:L/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
groups.google.com/g/golang-announce/c/EdhZqrQ98hk [email protected] groups.google.com Release Notes
pkg.go.dev/vuln/GO-2026-4599 [email protected] pkg.go.dev Vendor Advisory
go.dev/issue/77952 [email protected] go.dev Issue Tracking
go.dev/cl/752182 [email protected] go.dev Mailing List
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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