QID 355167

a security vulnerability has been identified in all supported versions of openssl related to the verification of x.509 certificate chains that include policy constraints.
Attackers may be able to exploit this vulnerability by creating a malicious certificate chain that triggers exponential use of computational resources, leading to a denial-of-service (dos) attack on affected systems.
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. (
( CVE-2023-0464) 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.
( CVE-2023-0465) 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.
Certificate policy checks are disabled by default in openssl and are not commonly used by applications.

Successful exploitation of this vulnerability could lead to a securitybreach or could affect integrity, availability, and confidentiality.