CVE-2026-8389 JIT miscompilation in the JavaScript Engine: JIT component

High 8.8 Published 12 May 2026 Updated 15 Jul 2026

A JIT miscompilation flaw in Firefox allows attackers to execute arbitrary code or cause a denial of service.

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 CVE-2026-8389?

CVE-2026-8389 is a high-severity memory corruption vulnerability in Mozilla Firefox, published on 12 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

JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 150.0.3.

Weakness: CWE-733, CWE-843, CWE-686, CWE-119

Which versions are affected by CVE-2026-8389?

It affects 1 product.

Products include Mozilla Firefox.

How do I fix CVE-2026-8389?

No fix has been published for CVE-2026-8389 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-8389 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-8389 exists.

Public exploit code: 1 proofs of concept on GitHub.

All Mozilla Firefox vulnerabilities

Sources

Also known as GHSA-qh6r-h4hf-pr8w, UBUNTU-CVE-2026-8389.