CVE-2026-42765
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk32th percentile - higher than 32% of all known CVEs
Summary
The vulnerability occurs when partial-chain certificate verification is enabled along with OCSP response checking for the entire chain. If there is no self-signed trusted anchor, a NULL pointer dereference occurs, crashing the process.
Risk Assessment
A NULL pointer dereference can trigger a crash, leading to a Denial of Service (DoS) for the application. Applications that enable both verifications are at risk.
Recommendation
It is recommended not to enable both OCSP verification for the entire chain and partial chain verification simultaneously to avoid potential crashes. Users should also monitor their certificate configurations.
Original NVD description (English source)
Issue summary: When a partial-chain certificate verification is enabled together with OCSP response checking for the whole chain, a NULL dereference will happen if the verified chain does not have a self-signed trusted anchor, crashing the process. Impact summary: A NULL pointer dereference can trigger a crash which leads to a Denial of Service for an application. When performing OCSP response checking for certificates in the verification chain, the code always tries to access the next certificate as the issuer. There is a check for a self-signed certificate. However with the partial chain verification enabled when the chain does not have a self-signed trusted anchor, the issuer will be NULL for the last certificate in the chain. A NULL pointer dereference then happens. This issue affects only applications which enable both OCSP verification of the certificate chain (X509_V_FLAG_OCSP_RESP_CHECK_ALL) and partial chain verification (X509_V_FLAG_PARTIAL_CHAIN) in the certificate verification. Both flags are disabled by default. For that reason, we have assigned Low severity to the issue. No FIPS modules are affected by this issue as the affected code is outside the OpenSSL FIPS module boundary.