CVE-2026-3994
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 vulnerability was detected in rui314 mold up to 2.40.4. This issue affects the function mold::ObjectFilemold::X86_64::initialize_sections of the file src/input-files.cc of the component Object File Handler. Performing a manipulation results in heap-based buffer overflow. Attacking locally is a requirement. The exploit is now public and may be used. The project was informed of the problem early through an issue report but has not responded yet.
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 confidenceA heap-based buffer overflow vulnerability exists in the mold linker (versions up to 2.40.4) within the ObjectFile X86_64 initialize_sections function in src/input-files.cc. The vulnerability is triggered when processing malformed object files, allowing local attackers to overflow heap buffers during section initialization.
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
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/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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Determine if mold linker is installedRun 'mold --version' or check for the mold binary in common locations such as /usr/bin/mold, /usr/local/bin/mold, or via 'which mold'Affected if mold is not installed, the vulnerability does not apply
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Identify the installed mold versionExecute 'mold --version' and note the version number printed (format typically shows like 'mold X.Y.Z' or just the version number)Affected if The installed version is 2.40.4 or any earlier version (any version up to and including 2.40.4 is affected)
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Verify the binary or source file presenceCheck for the presence of the mold binary or source code in /usr/bin/mold, /usr/local/bin/mold, or the source file src/input-files.cc if built from sourceAffected if The vulnerable binary or source exists on the system, making the vulnerability potentially reachable
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Assess if mold processes untrusted object filesReview system or build workflows to determine whether mold is run against object files from untrusted or external sources, or if it is only used in controlled build environments with trusted inputAffected if mold is used to link or process object files from untrusted or user-supplied sources, the attack vector is present
The system is affected if mold linker version 2.40.4 or any earlier version is installed AND it processes object files from untrusted or external sources.
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 dataUpgrade to a patched version when available; until then, restrict processing of untrusted object files and avoid running mold on locally supplied files from untrusted sources.
- Consultation4.0 h
- Implementation2.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-3994 — 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-2026-3994 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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