CVE-2026-103602: Name constraints bypass via trailing dot in rfc822Name, dNSName and URI hosts

Published Oct 2, 2026
·
Updated

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.

Affected Software

1 affected component
Legion of the Bouncy Castle Inc. bc-csharp<2.7.0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade bc-csharp to a version that resolves this vulnerability.

    Fixed in 2.7.0

Event History

Oct 2, 2026
CVE Published
via MITRE·07:10 AM
Data Sourced
via MITRE·07:10 AM
DescriptionWeakness
Data Sourced
via NVD·08:17 AM
DescriptionSeverityWeakness

Contact

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