CVE-2017-12972

In Nimbus JOSE+JWT before 4.39, there is no integer-overflow check when converting length values from bytes to bits, which allows attackers to conduct HMAC bypass attacks by shifting Additional Authenticated Data (AAD) and ciphertext so that different plaintext is obtained for the same HMAC.

In Nimbus JOSE+JWT before 4.39, there is no integer-overflow check when converting length values from bytes to bits, which allows attackers to conduct HMAC bypass attacks by shifting Additional Authenticated Data (AAD) and ciphertext so that different plaintext is obtained for the same HMAC.

En Nimbus JOSE+JWT en versiones anteriores a la 4.39 no hay comprobación de desbordamiento de enteros al convertir valores de longitud de bytes a bits, lo que permite que atacantes lleven a cabo ataques de omisión HMAC mediante el cambio de Additional Authenticated Data (AAD) y texto cifrado. Así, se obtiene texto plano diferente a partir del mismo HMAC.