FFC-DH Peer Validation Uses Attacker-Supplied q

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CVE-2026-42770

CVE-2026-42770 affects OpenSSL FIPS modules (4.0, 3.6, 3.5, 3.4, 3.0) and related deployments using EVP_PKEY_derive_set_peer() with DHX/X9.42 keys. The vulnerability arises when the subgroup check Y^q ≡ 1 (mod p) uses the peer’s q instead of the local key’s q, allowing a malicious X9.42 peer to c...

CVE-2026-42770 FFC-DH Peer Validation Uses Attacker-Supplied q

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 FFC-DH Peer Validation Uses Attacker-Supplied q

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 FFC-DH Peer Validation Uses Attacker-Supplied q

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...

UBUNTU-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...