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. The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.
History

Mon, 13 Apr 2026 13:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Mon, 13 Apr 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-190
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.8, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:H'}

threat_severity

Low


Wed, 08 Apr 2026 19:45:00 +0000

Type Values Removed Values Added
First Time appeared Openssl
Openssl openssl
Vendors & Products Openssl
Openssl openssl

Tue, 07 Apr 2026 22:15:00 +0000

Type Values Removed Values Added
Description 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. The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.
Title Heap Buffer Overflow in Hexadecimal Conversion
Weaknesses CWE-787
References

cve-icon MITRE

Status: PUBLISHED

Assigner: openssl

Published: 2026-04-07T22:00:54.983Z

Updated: 2026-04-13T13:04:17.163Z

Reserved: 2026-03-09T15:56:53.191Z

Link: CVE-2026-31789

cve-icon Vulnrichment

Updated: 2026-04-13T13:00:34.871Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-04-07T22:16:21.617

Modified: 2026-04-08T21:27:00.663

Link: CVE-2026-31789

cve-icon Redhat

Severity : Low

Publid Date: 2026-04-07T00:00:00Z

Links: CVE-2026-31789 - Bugzilla