CVE-2026-35188

/// Technical description

Issue summary: A malicious server can exploit TLS OCSP stapling by delivering

a crafted response through the status_request extension, triggering a

double-free in the client's certificate verification path.

Impact summary: Successful exploitation allows an attacker to corrupt heap

memory via a double-free, potentially leading to a Denial of Service or

possibly an attacker controlled code execution or other undefined behavior.

If OCSP stapling is enabled and the TLS client connects to a malicious server,

a crafted OCSP stapled response can trigger a double free in the TLS client

when the stapled response is checked.

The OCSP stapling is not enabled by default. Reliable code execution

through a double-free is technically complex and highly environment-dependent

but the Denial of Service impact is straightforward to achieve, warranting

Moderate severity.

No FIPS modules are affected by this issue as the affected code is outside

the OpenSSL FIPS module boundary.

/// 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