# CVE-2019-11736: Race condition in Firefox

> A race condition in the Mozilla Maintenance Service allows local attackers to replace privileged executables, leading to privilege escalation on Windows systems.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Sep 2019
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-g4fc-6wpg-63m2, UBUNTU-CVE-2019-11736

## What is CVE-2019-11736?

CVE-2019-11736 is a high-severity vulnerability in Mozilla Firefox, published on 27 Sep 2019. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The Mozilla Maintenance Service does not guard against files being hardlinked to another file in the updates directory, allowing for the replacement of local files, including the Maintenance Service executable, which is run with privileged access. Additionally, there was a race condition during checks for junctions and symbolic links by the Maintenance Service, allowing for potential local file and directory manipulation to be undetected in some circumstances. This allows for potential privilege escalation by a user with unprivileged local access. <br>*Note: These attacks requires local system access and only affects Windows. Other operating systems are not affected.*. This vulnerability affects Firefox < 69 and Firefox ESR < 68.1.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2019-11736?

It affects 2 products.


Products: Mozilla Firefox, Mozilla Firefox Esr.

## How do I fix CVE-2019-11736?

Upgrade to a fixed version.

## Is CVE-2019-11736 being exploited?

There is no known exploitation of CVE-2019-11736 in the wild and no public exploit code.

## 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-2019-11736 and fix it if it is affected.

What it is: CVE-2019-11736 is a high-severity vulnerability in Mozilla Firefox, published on 27 Sep 2019. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-11736 in the wild and no public exploit code.

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-2019-11736/ (Markdown: https://insights.sbomify.com/CVE-2019-11736/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-11736
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-11736
- OSV: https://osv.dev/vulnerability/CVE-2019-11736

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-11736/
Summaries are generated and may contain mistakes; the official description above is the record.