CVE-2015-3196

ssl/s3_clnt.c en OpenSSL 1.0.0 en versiones anteriores a 1.0.0t, 1.0.1 en versiones anteriores a 1.0.1p y 1.0.2 en versiones anteriores a 1.0.2d, cuando es utilizado por un cliente multi hilo, escribe la pista de identidad PSK en una estructura de datos incorrecta, lo que permite a servidores remotos provocar una denegación de servicio (condición de carrera y liberación doble) a través de un mensaje ServerKeyExchange manipulado.

A race condition flaw, leading to a double free, was found in the way OpenSSL handled pre-shared key (PSK) identify hints. A remote attacker could use this flaw to crash a multi-threaded SSL/TLS client using OpenSSL.

There is a carry propagating bug in the x86_64 Montgomery squaring procedure. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH are considered just feasible (although very difficult) because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be very significant and likely only accessible to a limited number of attackers. An attacker would additionally need online access to an unpatched system using the target private key in a scenario with persistent DH parameters and a private key that is shared between multiple clients. For example this can occur by default in OpenSSL DHE based SSL/TLS ciphersuites. Other issues were also addressed.