Vulnerability in wolfEngine Affecting AES-GCM Encryption

CVE-2026-81020

What is CVE-2026-81020?

wolfEngine versions before 1.4.1 exhibit a significant vulnerability where an 8-byte explicit AES-GCM nonce is generated once upon setting the TLS write key. This critical oversight leads to the same key and nonce pair being reused across every TLS 1.2 and DTLS 1.2 AES-GCM record within a session. Consequently, this reuse compromises the confidentiality of encrypted messages, allowing an attacker who knows one ciphertext to infer others, thus revealing the keystream. This flaw also risks exposing the GHASH authentication key, potentially enabling the forgery of authentication tags. Notably, other encryption modes like AES-CCM, TLS 1.3, and non-TLS applications of the cipher remain unaffected.

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