CVE-2026-103602

Name constraints bypass via trailing dot in rfc822Name, dNSName and URI hosts

State
Published
Severity
8.2 High
Published
Oct 2, 2026
Updated
Oct 2, 2026
Reserved
Sep 30, 2026

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Description

Improper certificate validation in PkixNameConstraintValidator in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who controls, or can obtain certificates from, a name-constrained intermediate CA to have certificates accepted during PKIX certification path validation for email addresses, DNS names or URI hosts that lie within excluded subtrees applying to that CA, via an rfc822Name, dNSName or uniformResourceIdentifier name whose host ends with a dot, because names and constraints were compared without first removing the RFC 1034 root-label trailing dot, so a fully qualified host name did not match an excluded subtree for the same host written without the dot.

Scores

CVSSScoreVectorSource
4.08.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:Nbcorg

Weaknesses

  • CWE-295 Improper Certificate Validation

Affected Products

ProductVersions
bc-csharpLegion of the Bouncy Castle Inc.
  • before 2.7.0Affected

References

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