Heap-based buffer overflow in OpenSSL - CVE-2026-31789
Published: April 9, 2026
Vulnerability identifier: #VU125568
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-31789
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: OpenSSL Software Foundation
Affected software:
OpenSSL
OpenSSL
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to heap-based buffer overflow in hexadecimal conversion when converting an excessively large OCTET STRING value from an untrusted X.509 certificate to a hexadecimal string on 32-bit platforms. A remote attacker can supply a crafted X.509 certificate to execute arbitrary code.
Only 32-bit platforms are affected, and exploitation requires printing or logging untrusted X.509 certificates containing an OCTET STRING value larger than 1 gigabyte.
How to mitigate CVE-2026-31789
Install security update from vendor's website.