FreeBSD: VID-7caebe30-d7f1-11e6-a9a5-b499baebfeaf (CVE-2016-7056): openssl -- timing attack vulnerability

Cesar Pereida Garcia reports: The signing function in crypto/ecdsa/ecdsa_ossl.c in certain OpenSSL versions and forks is vulnerable to timing attacks when signing with the standardized elliptic curve P-256 despite featuring constant-time curve operations and modular inversion. A software defect omits setting the BN_FLG_CONSTTIME flag for nonces, failing to take a secure code path in the BN_mod_inverse method and therefore resulting in a cache-timing attack vulnerability. A malicious user with local access can recover ECDSA P-256 private keys.