CVE-2026-2681
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 · uneditedA flaw was found in the blst cryptographic library. This out-of-bounds stack write vulnerability, specifically in the blst_sha256_bcopy assembly routine, occurs due to a missing zero-length guard. A remote attacker can exploit this by providing a zero-length salt parameter to key generation functions, such as blst_keygen_v5(), if the application exposes this functionality. Successful exploitation leads to memory corruption and immediate process termination, resulting in a denial-of-service (DoS) condition.
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 · moderate confidenceThe blst cryptographic library contains an out-of-bounds stack write vulnerability in the blst_sha256_bcopy assembly routine caused by a missing zero-length guard. When a zero-length salt parameter is passed to key generation functions like blst_keygen_v5(), the missing validation leads to memory corruption and process termination, resulting in denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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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Identify blst library installationSearch for blst library files on the system using commands like 'find /usr -name "*blst*"' or check package managers for installed blst packagesAffected if The blst library is present on the system
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Determine blst library versionCheck the installed version via package manager (dpkg -l | grep blst, rpm -qa | grep blst) or by inspecting library files (strings libblst.so | grep -i version)Affected if The installed version lacks the zero-length guard fix (compare your version to any available fixed releases)
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Identify usage of vulnerable key generation functionsSearch source code for calls to blst_keygen_v5() or similar functions (blst_keygen, blst_keygen_v4) that accept a salt parameterAffected if Code calls blst_keygen_v5() or related key generation functions with external or user-controlled salt input
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Verify salt parameter handlingInspect the code paths that pass salt to blst_keygen_v5() to determine if zero-length salt values can reach the vulnerable functionAffected if Zero-length salt values are not validated before being passed to the key generation function
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Test for denial of service conditionIf feasible in a test environment, invoke blst_keygen_v5() with an empty/zero-length salt parameter and observe if the process terminates unexpectedlyAffected if Passing a zero-length salt causes process termination or crash
A user is affected if their system has the blst library installed, uses blst_keygen_v5() or similar functions, and does not validate that salt parameters have non-zero length before passing them to the library.
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.
From vendor dataImplement input validation to reject zero-length salt parameters before calling blst_keygen_v5() and similar key generation functions, or update the blst library to a version containing the fix if available.
- Consultation4.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,392.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-2681 — 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-2026-2681 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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- Version or environment caveats, and links to real fixes
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