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OpenSSL CVE-2026-31789

| EUVDEUVD-2026-19968 CRITICAL
Out-of-bounds Write (CWE-787)
2026-04-07 openssl GHSA-j79m-9jxq-788r
Memory Corruption OpenSSL Buffer Overflow RCE
Critical
Disputed · 9.8 NVD
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Severity by source

Sources disagree (Low–Critical)
NVD PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SUSE
CRITICAL
qualitative
Red Hat
5.8 LOW
qualitative

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

4
CVSS changed
Apr 23, 2026 - 16:12 NVD
9.8 (CRITICAL)
EUVD ID Assigned
Apr 07, 2026 - 22:16 euvd
EUVD-2026-19968
Patch released
Apr 07, 2026 - 22:16 nvd
Patch available
CVE Published
Apr 07, 2026 - 22:00 nvd
N/A

DescriptionCVE.org

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.

Analysis

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.

Technical ContextAI

An out-of-bounds memory access occurs when code reads from or writes to memory locations outside the intended buffer boundaries. This vulnerability is classified as Out-of-bounds Write (CWE-787).

RemediationAI

A vendor patch is available — apply it immediately. Implement proper bounds checking on all array and buffer accesses. Use memory-safe languages or static analysis tools to detect OOB issues.

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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
Container private-registry/1.2/harbor-portal:1.2.0-1.8 Container private-registry/harbor-portal:1.1.2-2.17 Container suse/multi-linux-manager/5.1/x86_64/server-postgresql:5.1.3.6.18.1 Affected
Container suse/manager/4.3/proxy-httpd:4.3.17.9.76.9 Container suse/manager/4.3/proxy-squid:4.3.17.9.75.7 Container suse/manager/4.3/proxy-ssh:4.3.17.9.66.7 Affected
Container suse/manager/4.3/proxy-salt-broker:4.3.17.9.66.9 Container suse/manager/4.3/proxy-tftpd:4.3.17.9.66.8 Affected
Container suse/multi-linux-manager/5.1/x86_64/proxy-httpd:5.1.3.8.18.1 Container suse/multi-linux-manager/5.1/x86_64/proxy-squid:5.1.3.8.16.1 Container suse/multi-linux-manager/5.1/x86_64/proxy-ssh:5.1.3.8.16.1 Container suse/multi-linux-manager/5.1/x86_64/server-migration-14-16:5.1.3.8.16.1 Affected
Container suse/multi-linux-manager/5.1/x86_64/proxy-salt-broker:5.1.3.9.16.1 Container suse/multi-linux-manager/5.1/x86_64/proxy-tftpd:5.1.3.8.16.1 Container suse/multi-linux-manager/5.1/x86_64/server-saline:5.1.3.9.16.1 Container suse/multi-linux-manager/5.1/x86_64/server:5.1.3.8.16.1 Affected

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CVE-2026-31789 vulnerability details – vuln.today
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