NULL Dereference in OpenSSL Certificate Verification with OCSP Checking
CVE-2026-42765 is a NULL pointer dereference in OpenSSL certificate verification logic. The issue occurs when partial-chain verification is enabled together with OCSP response checking for the entire certificate chain. During OCSP response checking, the code assumes the next certificate in the verified chain is available as the issuer and attempts to access it. Although there is handling for self-signed certificates, when X509_V_FLAG_PARTIAL_CHAIN is enabled and the verified chain does not include a self-signed trusted anchor, the issuer for the last certificate in the chain is NULL. Dereferencing that NULL pointer causes the process to crash. The vulnerability affects OpenSSL 4.0.0 before 4.0.1 and 3.6.0 before 3.6.3. The affected code is outside the OpenSSL FIPS module boundary, and no FIPS modules are affected.
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Recent activity
2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An OpenSSL NULL pointer dereference vulnerability in partial-chain certificate verification and OCSP status response processing that can cause an immediate server crash.
A low-severity OpenSSL NULL dereference in certificate verification when OCSP checking for the whole chain is combined with partial-chain verification, leading to denial of service.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.