A type confusion vulnerability was found in OpenSSL when OpenSSL X.400 addresses processing inside an X.509 GeneralName. When CRL checking is enabled (for example, the application sets the X509_V_FLAG_CRL_CHECK flag), this vulnerability may allow an attacker to pass arbitrary pointers to a memcmp call, enabling them to read memory contents or cause a denial of service. In most cases, the attack requires the attacker to provide both the certificate chain and CRL, of which neither needs a valid signature. If the attacker only controls one of these inputs, the other input must already contain an X.400 address as a CRL distribution point, which is uncommon. In this case, this vulnerability is likely only to affect applications that have implemented their own functionality for retrieving CRLs over a network.