A malicious TLS server can send a crafted OCSP stapled response via the status_request extension to a client that has OCSP stapling enabled. The OpenSSL client library then performs the certificate verification and, due to a double‑free bug, releases memory that is still in use. The resulting heap corruption can lead to a service disruption or, if successfully exploited, to arbitrary code execution on the client. The flaw is a classic CWE‑415 double‑free vulnerability.

The vulnerability affects the OpenSSL library. No specific version range is provided, and OCSP stapling is not enabled by default. FIPS modules are not affected, as the code that misbehaves lies outside the FIPS module boundary.

The risk level is moderate because a denial‑of‑service outcome is straightforward to achieve, while reliable code execution requires a complex combination of conditions. The CVSS score for this vulnerability is 5, indicating moderate severity. The EPSS score is < 1% (approximately 0.00017), and the vulnerability is not listed in the CISA KEV catalog. Exploitation requires the attacker to control the TLS server and send a malformed stapled response to a client that has OCSP stapling enabled. The attack surface is therefore limited to TLS clients that have enabled this feature, and the attacker must first be able to establish a TLS connection to the client.