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CVE-2026-42765 is a NULL pointer dereference vulnerability in OpenSSL certificate verification logic. It occurs when partial-chain verification is enabled together with OCSP response checking for the entire certificate chain. During OCSP response validation, the code assumes that the next certificate in the verified chain is available as the issuer certificate. Although there is handling for self-signed certificates, this assumption fails when partial-chain verification is used and the verified chain terminates without a self-signed trusted anchor. In that case, the issuer reference for the last certificate in the chain is NULL, and dereferencing it causes the process to crash. The issue affects OpenSSL 4.0.0 before 4.0.1 and 3.6.0 before 3.6.3. Both required verification flags are disabled by default, which limits exposure.
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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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Every observed campaign linking this CVE to a named adversary.
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Cross-references every affected SKU, including bundled OEM variants.
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