CVE-2015-3195

La implementación ASN1_TFLG_COMBINE en crypto/asn1/tasn_dec.c en OpenSSL en versiones anteriores a 0.9.8zh, 1.0.0 en versiones anteriores a 1.0.0t, 1.0.1 en versiones anteriores a 1.0.1q y 1.0.2 en versiones anteriores a 1.0.2e no maneja correctamente los errores provocados por datos X509_ATTRIBUTE malformados, lo que permite a atacantes remotos obtener información sensible de memoria de proceso desencadenando un fallo de decodificación en una aplicación PKCS#7 o CMS.

A memory leak vulnerability was found in the way OpenSSL parsed PKCS#7 and CMS data. A remote attacker could use this flaw to cause an application that parses PKCS#7 or CMS data from untrusted sources to use an excessive amount of memory and possibly crash.

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.