CVE-2023-0286: X.400 address type confusion in X.509 GeneralName

pyca/cryptography's wheels include a statically linked copy of OpenSSL. The versions of OpenSSL included in cryptography 0.8.1-39.0.0 are vulnerable to a security issue. More details about the vulnerabilities themselves can be found in https://www.openssl.org/news/secadv/20221213.txt and https://www.openssl.org/news/secadv/20230207.txt.

If you are building cryptography source ("sdist") then you are responsible for upgrading your copy of OpenSSL. Only users installing from wheels built by the cryptography project (i.e., those distributed on PyPI) need to update their cryptography versions.

— GitHub

There is a type confusion vulnerability relating to X.400 address processing inside an X.509 GeneralName. X.400 addresses were parsed as an ASN1STRING but the public structure definition for GENERALNAME incorrectly specified the type of the x400Address field as ASN1TYPE. This field is subsequently interpreted by the OpenSSL function GENERALNAMEcmp as an ASN1TYPE rather than an ASN1STRING.

When CRL checking is enabled (i.e. the application sets the X509VFLAGCRLCHECK flag), this vulnerability may allow an attacker to pass arbitrary pointers to a memcmp call, enabling them to read memory contents or enact a denial of service. In most cases, the attack requires the attacker to provide both the certificate chain and CRL, neither of which need to have 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. As such, this vulnerability is most likely to only affect applications which have implemented their own functionality for retrieving CRLs over a network.

— NVD