# CVE-2024-3859: Integer overflow in Firefox

> Integer overflows in 32-bit Firefox and Thunderbird allow out-of-bounds reads via malformed OpenType fonts, potentially causing crashes or data exposure.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:N`)
- **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:** Yes
- **Published:** 16 Apr 2024
- **Updated:** 1 Aug 2024
- **Also known as:** DEBIAN-CVE-2024-3859, GHSA-6f82-r7wj-8fxf, UBUNTU-CVE-2024-3859

## What is CVE-2024-3859?

CVE-2024-3859 is a medium-severity vulnerability in Debian Debian Linux, published on 16 Apr 2024. 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

On 32-bit versions there were integer-overflows that led to an out-of-bounds-read that potentially could be triggered by a malformed OpenType font. This vulnerability affects Firefox < 125, Firefox ESR < 115.10, and Thunderbird < 115.10.

Weakness: CWE-190 (Integer Overflow or Wraparound), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2024-3859?

It affects 3 products.


Products: Debian Debian Linux, Mozilla Firefox, Mozilla Thunderbird.

## How do I fix CVE-2024-3859?

Upgrade to a fixed version.

## Is CVE-2024-3859 being exploited?

There is no known exploitation of CVE-2024-3859 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-2024-3859 and fix it if it is affected.

What it is: CVE-2024-3859 is a medium-severity vulnerability in Debian Debian Linux, published on 16 Apr 2024. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2024-3859 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-2024-3859/ (Markdown: https://insights.sbomify.com/CVE-2024-3859/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-3859
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-3859
- OSV: https://osv.dev/vulnerability/CVE-2024-3859

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-3859/
Summaries are generated and may contain mistakes; the official description above is the record.