openssl: FFC-DH Peer Validation Uses Attacker-Supplied q

A flaw was found in OpenSSL. A malicious peer can exploit this vulnerability by presenting a specially crafted DHX X9.42 peer key. Due to improper validation of the peer key's subgroup membership, an attacker can recover the victim's private key after a small number of key exchange attempts. This...

CVE-2026-42770

Issue summary: When EVPPKEYderivesetpeer is called with a DHX X9.42 peer key, the peer key is not properly checked for the subgroup membership. Impact summary: A malicious peer which presents an X9.42 key carrying the victim's p and g parameters, a forged q = r a small prime factor of the cofacto...

CVE-2026-42770

Issue summary: When EVPPKEYderivesetpeer is called with a DHX X9.42 peer key, the peer key is not properly checked for the subgroup membership. Impact summary: A malicious peer which presents an X9.42 key carrying the victim's p and g parameters, a forged q = r a small prime factor of the cofacto...