CVE-2020-1971

A null pointer dereference flaw was found in openssl. A remote attacker, able to control the arguments of the GENERAL_NAME_cmp function, could cause the application, compiled with openssl to crash resulting in a denial of service. The highest threat from this vulnerability is to system availability.

This is a flaw in the GENERAL_NAME_cmp function of openssl which can be triggered when both its arguments are of the same type i.e. EDIPARTYNAME.

1. Red Hat does not ship any applications compiled with openssl, which used the above function in a vulnerable way.

2. OpenSSL itself uses the GENERAL_NAME_cmp function for two purposes, when comparing CRL distribution point names between an available CRL and a CRL distribution point embedded in an X509 certificate and when verifying that a timestamp response token signer matches the timestamp authority name (exposed via the API functions TS_RESP_verify_response and TS_RESP_verify_token). If an attacker can control both items being compared then that attacker could trigger a crash. For example, if the attacker can trick a client or server into checking a malicious certificate against a malicious CRL then a crash may be triggered.

Third party applications compiled with openssl using the function GENERAL_NAME_cmp in a vulnerable way are affected by this flaw.

GENERAL_NAME_cmp was added in 0.9.8k, therefore older versions of openssl are not affected by this flaw.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Applications not using the GENERAL_NAME_cmp of openssl are not vulnerable to this flaw. Even when this function is used, if the attacker can control both the arguments of this function, only then the attacker could trigger a crash.