Is CVE-2026-120440 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-120440?

CVE-2026-120440 has a CVSS v3 severity of MEDIUM (5.3).

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CVE-2026-120440

Description

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.