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

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

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **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 available:** No
- **Published:** 12 May 2026
- **Updated:** 15 Jul 2026
- **Also known as:** GHSA-qh6r-h4hf-pr8w, UBUNTU-CVE-2026-8389

## 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 (Compiler Optimization Removal or Modification of Security-critical Code), CWE-843 (Access of Resource Using Incompatible Type), CWE-686 (Function Call With Incorrect Argument Type), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-8389?

It affects 1 product.


Products: 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.

## 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:

- https://github.com/crixpwn/CVE-2026-8389 (github_poc): https://github.com/crixpwn/CVE-2026-8389

## Other vulnerabilities in Mozilla Firefox

- [CVE-2019-11708](https://insights.sbomify.com/CVE-2019-11708/): Mozilla Firefox and Thunderbird Sandbox Escape (critical 10.0, exploited in the wild)
- [CVE-2010-3765](https://insights.sbomify.com/CVE-2010-3765/): Mozilla Multiple Products Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2022-26486](https://insights.sbomify.com/CVE-2022-26486/): Mozilla Firefox Use-After-Free (critical 9.6, exploited in the wild)
- [CVE-2022-26485](https://insights.sbomify.com/CVE-2022-26485/): Mozilla Firefox Use-After-Free (high 8.8, exploited in the wild)
- [CVE-2019-11707](https://insights.sbomify.com/CVE-2019-11707/): Mozilla Firefox and Thunderbird Type Confusion (high 8.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-8389 and fix it if it is affected.

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

Affected product: Mozilla Firefox. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-8389/ (Markdown: https://insights.sbomify.com/CVE-2026-8389/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8389
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8389
- OSV: https://osv.dev/vulnerability/CVE-2026-8389

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-8389/
Summaries are generated and may contain mistakes; the official description above is the record.