CVE-2026-33810 PUBLISHED

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

Assigner: Go
Reserved: 23.03.2026 Published: 08.04.2026 Updated: 08.04.2026

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.

Product Status

Vendor Go standard library
Product crypto/x509
Versions Default: unaffected
  • affected from 1.26.0-0 to 1.26.2 (excl.)

Credits

  • Riyas from Saintgits College of Engineering
  • k1rnt
  • @1seal

References

Problem Types

  • CWE-295: Improper Certificate Validation