CVE-2026-42765

Description

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.

PUBLISHED Reserved 2026-04-29 | Published 2026-06-09 | Updated 2026-06-10 | Assigner openssl

Problem types

CWE-476 NULL Pointer Dereference

Product status

Credits

Joshua Rogers (Aisle Research) reporter

Joshua Rogers (Aisle Research) remediation developer

Daniel Kubec remediation developer

References

openssl-library.org/news/secadv/20260609.txt (OpenSSL Advisory) vendor-advisory

github.com/...ommit/14340b7fa1d444615486bc137014b064e64ec334 (4.0.1 git commit) patch

github.com/...ommit/eb345da18ce2216b2f3ade9c2bc23e068487fa97 (3.6.3 git commit) patch

cve.org (CVE-2026-42765)

nvd.nist.gov (CVE-2026-42765)

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