RUSTSEC-2021-0058

Null pointer deref in `X509_issuer_and_serial_hash()`

The OpenSSL public API function `X509_issuer_and_serial_hash()` attempts to create a unique hash value based on the issuer and serial number data contained within an X509 certificate. However it fails to correctly handle any errors that may occur while parsing the issuer field (which might occur if the issuer field is maliciously constructed). This may subsequently result in a NULL pointer deref and a crash leading to a potential denial of service attack. The function `X509_issuer_and_serial_hash()` is never directly called by OpenSSL itself so applications are only vulnerable if they use this function directly and they use it on certificates that may have been obtained from untrusted sources.