CVE-2023-0466

A flaw was found in OpenSSL. The X509_VERIFY_PARAM_add0_policy() function is documented to enable the certificate policy check when doing certificate verification implicitly. However, implementing the function does not enable the check, allowing certificates with invalid or incorrect policies to pass the certificate verification. Suddenly enabling the policy check could break existing deployments, so it was decided to keep the existing behavior of the X509_VERIFY_PARAM_add0_policy() function. The applications that require OpenSSL to perform certificate policy check need to use X509_VERIFY_PARAM_set1_policies() or explicitly enable the policy check by calling X509_VERIFY_PARAM_set_flags() with the X509_V_FLAG_POLICY_CHECK flag argument. Certificate policy checks are disabled by default in OpenSSL and are not commonly used by applications.

The function X509_VERIFY_PARAM_add0_policy() is documented to implicitly enable the certificate policy check when doing certificate verification. However the implementation of the function does not enable the check which allows certificates with invalid or incorrect policies to pass the certificate verification. As suddenly enabling the policy check could break existing deployments it was decided to keep the existing behavior of the X509_VERIFY_PARAM_add0_policy() function. Instead the applications that require OpenSSL to perform certificate policy check need to use X509_VERIFY_PARAM_set1_policies() or explicitly enable the policy check by calling X509_VERIFY_PARAM_set_flags() with the X509_V_FLAG_POLICY_CHECK flag argument. Certificate policy checks are disabled by default in OpenSSL and are not commonly used by applications.

It was discovered that OpenSSL was not properly managing file locks when processing policy constraints. If a user or automated system were tricked into processing a certificate chain with specially crafted policy constraints, a remote attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 22.04 LTS and Ubuntu 22.10. David Benjamin discovered that OpenSSL was not properly performing the verification of X.509 certificate chains that include policy constraints, which could lead to excessive resource consumption. If a user or automated system were tricked into processing a specially crafted X.509 certificate chain that includes policy constraints, a remote attacker could possibly use this issue to cause a denial of service.