CVE-2026-54876

Technical Description

Issue summary: A malicious TLS server can cause a memory leak in a TLS

client that has enabled OCSP response checking by sending an OCSP

response that contains no single response entries.

Impact summary: An attacker can leak an attacker-tunable amount of memory

per TLS handshake in a victim client application. A long-running client

that repeatedly connects to a malicious server can have its memory

exhausted, resulting in a Denial of Service.

CWE: CWE-401: Missing Release of Memory after Effective Lifetime

Description: The affected function is called during X.509 certificate

chain verification when OCSP response checking is enabled

with the X509_V_FLAG_OCSP_RESP_CHECK or X509_V_FLAG_OCSP_RESP_CHECK_ALL

verification flags, for example when a TLS client verifies an OCSP

response stapled into the TLS handshake by the server.

When the received BasicOCSPResponse contains an empty SEQUENCE OF

SingleResponse, which is permitted on the wire and accepted by the

OpenSSL decoder, the OCSP_BASI

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References