CVE-2026-71885 MLS X.509 credential not bound to the LeafNode signature key

In Bouncy Castle for Java before 1.86, the Messaging Layer Security MLS, RFC 9420 implementation did not bind an X.509 credential to a LeafNode's signaturekey. LeafNode.verify checked a leaf's signature against the signaturekey carried in the leaf itself, while the credential's X.509 certificate...

PT-2026-104567

Name of the Vulnerable Software and Affected Versions Bouncy Castle for Java versions prior to 1.86 Description The Messaging Layer Security MLS, RFC 9420 implementation fails to bind an X.509 credential to a LeafNode signature key. The LeafNode.verify function validates a leaf signature against...