OpenSSLFramework / library
CVE-2026-31789
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIssue 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 summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceHeap buffer overflow in OpenSSL when converting oversized OCTET STRING values (from X.509 certificate extensions like SKID/AKID) to hexadecimal strings on 32-bit platforms. The buffer size calculation multiplies input length by 3, which can overflow on 32-bit systems, causing allocation of an undersized buffer and subsequent overflow when the hex string is written.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
OpenSSLFramework / library
>= 3.0.0, < 3.0.20>= 3.3.0, < 3.3.7>= 3.4.0, < 3.4.5>= 3.5.0, < 3.5.6>= 3.6.0, < 3.6.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check OpenSSL versionRun `openssl version` or inspect library file to obtain the version numberAffected if Version falls within any of these ranges: >= 3.0.0 and < 3.0.20; >= 3.3.0 and < 3.3.7; >= 3.4.0 and < 3.4.5; >= 3.5.0 and < 3.5.6; >= 3.6.0 and < 3.6.2
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Confirm platform architectureCheck system architecture (uname -m or similar) to determine if running on a 32-bit platformAffected if System is 32-bit (x86, i386, i686, or similar 32-bit architecture)
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Inspect certificate processing workflowReview logs, configurations, or code that processes X.509 certificates, particularly looking for handling of SKID (Subject Key Identifier) or AKID (Authority Key Identifier) extensionsAffected if Application processes X.509 certificates with large OCTET STRING values in extensions, especially certificates over 1GB in size on 32-bit platforms
You are affected if running a vulnerable OpenSSL version on a 32-bit platform and processing certificates larger than 1GB with large OCTET STRING extensions like SKID/AKID.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.0.203.3.73.4.5
Deploy on 64-bit platforms only, or wait for vendor patch and upgrade; avoid processing untrusted X.509 certificates with logging/printing functionality until patched.
OpenSSL 3.0.20+ (for 3.0.x branch), 3.3.7+ (for 3.3.x branch), 3.4.5+ (for 3.4.x branch), or 3.5.6+ (for 3.5.x branch)
- 1. Identify the currently installed OpenSSL version using: openssl version -a
- 2. Determine which OpenSSL 3.x branch is in use (3.0.x, 3.3.x, 3.4.x, or 3.5.x)
- 3. For systems using OpenSSL 3.0.x: upgrade to version 3.0.20 or later
- 4. For systems using OpenSSL 3.3.x: upgrade to version 3.3.7 or later
- 5. For systems using OpenSSL 3.4.x: upgrade to version 3.4.5 or later
- 6. For systems using OpenSSL 3.5.x: upgrade to version 3.5.6 or later
- 7. Verify the upgrade was successful by running: openssl version -a
- 8. Restart any services that depend on OpenSSL to load the updated libraries
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in OpenSSL
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,416.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-31789 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-31789 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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