CVE-2026-33810

HIGH 7.5

Case-sensitive excludedSubtrees name constraints cause Auth Bypass in crypto/x509

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a different case than the constraint. This only affects validation of otherwise trusted certificate chains, issued by a root CA in the VerifyOptions.Roots CertPool, or in the system certificate pool.

Vendor	go standard library
Product	crypto/x509
Published	Apr 8, 2026
Last Updated	Apr 13, 2026

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Affected Versions

Go standard library / crypto/x509

1.26.0-0 < 1.26.2

References

NVD ↗ CVE.org ↗ EPSS Data ↗

go.dev: https://go.dev/cl/763763 go.dev: https://go.dev/issue/78332 groups.google.com: https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU pkg.go.dev: https://pkg.go.dev/vuln/GO-2026-4866

Credits

Riyas from Saintgits College of Engineering k1rnt @1seal