CVE-2023-0465

A flaw was found in OpenSSL. Applications that use a non-default option when verifying certificates may be vulnerable to an attack from a malicious CA to circumvent certain checks. OpenSSL and other certificate policy checks silently ignore invalid certificate policies in leaf certificates that are skipped for that certificate. A malicious CA could use this to deliberately assert invalid certificate policies to circumvent policy checking on the certificate altogether. Policy processing is disabled by default but can be enabled by passing the `-policy' argument to the command line utilities or by calling the `X509_VERIFY_PARAM_set1_policies()' function.

Applications that use a non-default option when verifying certificates may be vulnerable to an attack from a malicious CA to circumvent certain checks. Invalid certificate policies in leaf certificates are silently ignored by OpenSSL and other certificate policy checks are skipped for that certificate. A malicious CA could use this to deliberately assert invalid certificate policies in order to circumvent policy checking on the certificate altogether. Policy processing is disabled by default but can be enabled by passing the `-policy' argument to the command line utilities or by calling the `X509_VERIFY_PARAM_set1_policies()' function.

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.