OSV-2026-703 Heap-use-after-free in js_atomics_op
A heap-use-after-free in the JavaScript engine allows attackers to execute arbitrary code or cause denial of service via crafted scripts.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is OSV-2026-703?
OSV-2026-703 is an use after free vulnerability in quickjs, published on 9 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=510792185
Crash type: Heap-use-after-free WRITE 4
Crash state:
js_atomics_op
js_call_c_function
JS_CallInternal
Which versions are affected by OSV-2026-703?
1 open source package ship an affected version, including quickjs.
| Package | Affected | Fixed in |
|---|---|---|
quickjs OSS-Fuzz | All versions | None |
How do I fix OSV-2026-703?
No fix has been published for OSV-2026-703 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is OSV-2026-703 being exploited?
There is no known exploitation of OSV-2026-703 in the wild and no public exploit code.