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CVE-2026-63577

Name Constraints bypass: directoryName constraint matched at any position in the DN instead of as a prefix PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
Legion of the Bouncy Castle Inc. / bc-csharpaffected 0 before 2.7.0

CWE

CWE-295

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.