Threats Tagged 'cve-2026-63577'

CVE-2026-63577 is a vulnerability in Legion of the Bouncy Castle Inc. bc-csharp before version 2.7.0 involving improper certificate validation. The flaw occurs in the directoryName name-constraint check within the PkixNameConstraintValidator.WithinDNSubtree function. It allows an attacker controlling or having certificates issued by a name-constrained intermediate CA to bypass PKIX path validation by crafting subject distinguished names or directoryName subjectAltNames that lie outside the permitted subtrees. This happens because the validation incorrectly searches for the constraint's first RDN anywhere in the name rather than requiring it as an initial prefix, violating RFC 5280 requirements. No patch or remediation information is provided. The vulnerability is rated high severity based on the described impact.

Improper certificate validation in the directoryName name-constraint check (PkixNameConstraintValidator.WithinDNSubtree) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who controls, or can have certificates issued by, a name-constrained intermediate CA to get certificates accepted by PKIX path validation whose subject distinguished name, or a directoryName subjectAltName, lies outside the CA's permitted subtrees, via a name that places other RDNs ahead of a copy of the permitted RDN sequence, because the check looks for the constraint's first RDN anywhere in the name and compares the remaining RDNs from that position, instead of requiring the constraint to be an initial prefix of the name as RFC 5280 sections 4.2.1.10 and 7.1 require.