OpenBao’s certificate authentication method allows an attacker who possesses a sibling certificate issued by the same CA to renew a token that was originally authenticated with a different certificate, provided the `disable_binding=true` flag is set. The flaw occurs because the system incorrectly verifies the presented certificate against the original during renewal, permitting the attacker to extend the life of dynamic leases or other privileges that were granted to the original token. This weakness is a certificate policy error (CWE‑295) and can be leveraged only when the attacker already knows the original token or its accessor, but it still allows undue persistence in the system.

Versions of OpenBao prior to v2.5.3 are affected. The vulnerability is present across all installations using the certificate authentication method with the `disable_binding` option enabled. The fix is delivered in OpenBao v2.5.3 and later.

The vulnerability has a CVSS score of 2, indicating low severity, and its EPSS score is not available. It is not listed in the CISA KEV catalog. Exploitation requires possession of a valid sibling certificate and either the original token or its accessor, making it a high‑skill attack rather than a widespread vulnerability. The availability of a public patch mitigates the risk significantly, but organizations still need to verify that the new version is deployed and that privileged certificates are appropriately scoped.