# CVE-2019-9792: Memory corruption in Firefox

> A flaw in the IonMonkey JIT compiler allows memory corruption via a leaked magic value, potentially leading to code execution or crashes in Firefox and Thunderbird.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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:** Not needed
- **Fix available:** Yes
- **Published:** 26 Apr 2019
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2019-9792, GHSA-83fw-4w4c-4v29, UBUNTU-CVE-2019-9792

## What is CVE-2019-9792?

CVE-2019-9792 is a critical memory corruption vulnerability in Mozilla Firefox, published on 26 Apr 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The IonMonkey just-in-time (JIT) compiler can leak an internal JS_OPTIMIZED_OUT magic value to the running script during a bailout. This magic value can then be used by JavaScript to achieve memory corruption, which results in a potentially exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2019-9792?

It affects 6 products.


Products: Mozilla Firefox, Mozilla Thunderbird, Redhat Enterprise Linux, Redhat Enterprise Linux Eus, Redhat Enterprise Linux Server Aus, Redhat Enterprise Linux Server Tus.

## How do I fix CVE-2019-9792?

Upgrade to a fixed version.

## Is CVE-2019-9792 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2019-9792 exists.

Public exploit code:

- Spidermonkey - IonMonkey Leaks JS_OPTIMIZED_OUT Magic Value to Script (exploitdb)

## 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-2019-9792 and fix it if it is affected.

What it is: CVE-2019-9792 is a critical memory corruption vulnerability in Mozilla Firefox, published on 26 Apr 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2019-9792 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-2019-9792/ (Markdown: https://insights.sbomify.com/CVE-2019-9792/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-9792
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-9792
- OSV: https://osv.dev/vulnerability/CVE-2019-9792

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-9792/
Summaries are generated and may contain mistakes; the official description above is the record.