# CVE-2026-120440: QuickJS-NG before 0.16.0 Memory Leak via Atomics.store

Status: published. Published: 2026-11-02. Updated: 2026-11-02.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- quickjs-ng / QuickJS-NG (quickjs-ng/quickjs): ≥ 0; < 0.16.0 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 5.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-401

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/quickjs-ng/quickjs/security/advisories/GHSA-wm7w-r6qf-3c9w (CNA: VulnCheck; vendor-advisory)

- https://github.com/quickjs-ng/quickjs/commit/62951e1bc68711d37aad986ff84ef0fe17038a7e (CNA: VulnCheck; patch)

- https://github.com/quickjs-ng/quickjs/releases/tag/v0.16.0 (CNA: VulnCheck; release-notes)

- https://github.com/quickjs-ng/quickjs/blob/v0.15.1/quickjs.c#L61154 (CNA: VulnCheck; technical-description)

- https://www.vulncheck.com/advisories/quickjs-ng-before-0.16.0-memory-leak-via-atomics-store (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-120440; retrieved 2026-11-02; source updated 2026-11-02

Revision: f1d1e4965219f2389e929eec6f2869a74df506582fffe4ee20be5c516c3b5ef8

Canonical: https://y2.dev/cve/CVE-2026-120440

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