CVE-2026-63573

A Bleichenbacher-style adaptive chosen-ciphertext attack exists in Legion of the Bouncy Castle Inc. bc-csharp versions before 2.7.0 . The vulnerability is located in the CMS RSA PKCS#1 v1.5 key-transport unwrap (KeyTransRecipientInformation.UnwrapKey) component. Because the system rejects ciphert...

CVE-2026-63573 Bleichenbacher padding oracle in CMS RSA PKCS#1 v1.5 key-transport unwrap

Observable discrepancy in the CMS RSA PKCS1 v1.5 key-transport unwrap KeyTransRecipientInformation.UnwrapKey in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker who holds a captured CMS EnvelopedData message, and who can submit many modified messages to an...