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VulnerabilityPublished

CVE-2026-3994: rui314 mold · Heap-based Buffer Overflow

Affects rui314 moldSource CVE Database V5

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Public exploit available · CVSS 4.8 Medium.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
4.8Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    CVSS exploit maturity: proof of concept public

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
rui314moldAffected
  • 2.40.0 – 2.40.4
5 affected builds
Fixed in–
GitHubrui314/moldpkg:github/rui314/moldOther threatsAffected
  • 2.40.0 – 2.40.4
5 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2026-3994, organizations should first restrict local access to systems running mold, ensuring only trusted users can execute the linker. Implement strict access controls and monitoring on build servers and developer workstations. Audit usage of mold and identify all systems with affected versions installed. Until an official patch is released, consider temporarily replacing mold with alternative linkers if feasible or running builds inside isolated containers or virtual machines to limit potential damage. Employ runtime protections such as heap memory protection mechanisms (e.g., ASLR, heap canaries) to reduce exploitation success. Monitor public advisories for patches or updates from the rui314 project and apply them promptly once available. Additionally, review build artifacts for integrity and consider implementing reproducible builds to detect tampering. Educate developers and system administrators about the risk of local exploitation and the importance of limiting local privilege escalation vectors.

Description

A 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.

References

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