CVE-2026-120440
CVE-2026-120440
QuickJS-NG before 0.16.0 contains a memory leak vulnerability in js_atomics_store() in quickjs.c that fails to free the converted value when returning a RangeError. Attackers running JavaScript can repeatedly call Atomics.store with a valueOf that detaches or shrinks the buffer to exhaust heap memory and cause denial of service.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Weakness classification (CWE)
References
- github.com/quickjs-ng/quickjs/security/advisories/GHSA-wm7w-r6qf-3c9w (vendor-advisory)
- github.com/quickjs-ng/quickjs/commit/62951e1bc68711d37aad986ff84ef0fe17038a7e (patch)
- github.com/quickjs-ng/quickjs/releases/tag/v0.16.0 (release-notes)
- github.com/quickjs-ng/quickjs/blob/v0.15.1/quickjs.c (technical-description)
- www.vulncheck.com/advisories/quickjs-ng-before-0.16.0-memory-leak-via-atomics-s… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-120440?
- CVE-2026-120440 is a medium-severity vulnerability, classified under Missing Release of Memory after Effective Lifetime. CVSS score: 5.3/10. Published 2026-11-02.
- How severe is CVE-2026-120440?
- Medium severity. CVSS v3 base score is 5.3 out of 10.