Bug 2451095 (CVE-2026-31789)

Summary: CVE-2026-31789 openssl: OpenSSL: Heap buffer overflow on 32-bit systems from large X.509 certificate processing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: csutherl, jclere, pjindal, plodge, security-response-team, szappis, vchlup
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in OpenSSL. This vulnerability, a heap buffer overflow, affects 32-bit systems when processing an unusually large X.509 certificate. If an application or service attempts to print or log such a specially crafted certificate, it could lead to a system crash or potentially allow an attacker to execute arbitrary code. This issue is considered low severity due to the specific conditions required for exploitation, including the need for an extremely large certificate and a 32-bit operating environment.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Deadline: 2026-04-07   

Description OSIDB Bzimport 2026-03-25 03:14:59 UTC 
Issue summary: Converting an excessively large OCTET STRING value to
a hexadecimal string leads to a heap buffer overflow on 32 bit platforms.

Impact summary: A heap buffer overflow may lead to a crash or possibly
an attacker controlled code execution or other undefined behavior.

If an attacker can supply a crafted X.509 certificate with an excessively
large OCTET STRING value in extensions such as the Subject Key Identifier
(SKID) or Authority Key Identifier (AKID) which are being converted to hex,
the size of the buffer needed for the result is calculated as multiplication
of the input length by 3. On 32 bit platforms, this multiplication may overflow
resulting in the allocation of a smaller buffer and a heap buffer overflow.

Applications and services that print or log contents of untrusted X.509
certificates are vulnerable to this issue. As the certificates would have
to have sizes of over 1 Gigabyte, printing or logging such certificates
is a fairly unlikely operation and only 32 bit platforms are affected,
this issue was assigned Low severity.