# CVE-2018-12379: Memory corruption in Firefox

> A memory corruption vulnerability in the Mozilla Updater allows attackers to trigger a crash or potentially execute code by providing a malicious MAR file.

- **Severity:** High 7.8 (`CVSS:3.0/AV:L/AC:L/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:** 18 Oct 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-12379, GHSA-77mg-phf5-3h8g

## What is CVE-2018-12379?

CVE-2018-12379 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 18 Oct 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

When the Mozilla Updater opens a MAR format file which contains a very long item filename, an out-of-bounds write can be triggered, leading to a potentially exploitable crash. This requires running the Mozilla Updater manually on the local system with the malicious MAR file in order to occur. This vulnerability affects Firefox < 62, Firefox ESR < 60.2, and Thunderbird < 60.2.1.

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

## Which versions are affected by CVE-2018-12379?

It affects 9 products.


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

## How do I fix CVE-2018-12379?

Upgrade to a fixed version.

## Is CVE-2018-12379 being exploited?

There is no known exploitation of CVE-2018-12379 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-12379 and fix it if it is affected.

What it is: CVE-2018-12379 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 18 Oct 2018. 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-2018-12379 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2018-12379/ (Markdown: https://insights.sbomify.com/CVE-2018-12379/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-12379
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-12379
- OSV: https://osv.dev/vulnerability/CVE-2018-12379

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-12379/
Summaries are generated and may contain mistakes; the official description above is the record.