PatchTheCVECVE-2026-120440: QuickJS-NG before 0.16.0 contains a memory leak vulnerability in js_atomics_store() in quickjs.c that fails to
CVE-2026-120440 is a medium-severity flaw (CVSS 5.3) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- Remotely exploitable, no login, no user action
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 5.3 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | n/a |
| CISA exploited list | No |
| Weakness | CWE-401 |
| Published | 2026-11-02 |
| Last modified | 2026-11-02 |
Last updated 2026-11-02 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Timeline
- Published CVE record published
- Updated Record last modified
Advisories and coverage
Research and news
- VulDB Recent Entries: CVE-2026-120440 | QuickJS-NG up to 0.15.x Atomics Store quickjs.c js_atomics_store memory leak 2026-11-02
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-120440?
No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.
Is CVE-2026-120440 being exploited?
CVE-2026-120440 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-120440 affect?
CVE-2026-120440 affects affected software. Severity is medium (CVSS 5.3). 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 value
How urgent is CVE-2026-120440?
Priority 24/100. Remotely exploitable, no login, no user action