NULL pointer dereference in OpenSSL - CVE-2026-42765
Published: June 10, 2026
Vulnerability identifier: #VU134280
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-42765
CWE-ID: CWE-476
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to NULL pointer dereference in certificate verification with OCSP checking when partial-chain verification is enabled together with OCSP response checking for the whole chain and the verified chain lacks a self-signed trusted anchor. A local user can trigger certificate verification on a crafted chain to cause a denial of service.
The issue affects only applications that enable both X509_V_FLAG_OCSP_RESP_CHECK_ALL and X509_V_FLAG_PARTIAL_CHAIN.
Affected software
OpenSSL
How to mitigate CVE-2026-42765
Install security update from vendor's website.
OpenSSL - addressed in versions 3.6.3, 4.0.1