CVE-2026-12803 KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery)

In Bouncy Castle for Java before 1.85, KCCMBlockCipher MAC does not bind nonce when AAD is absent cross-nonce AEAD forgery. This issue also affects Bouncy Castle for Java LTS before 2.73.12...