# CVE-2016-5287: Use after free in Firefox

> A use-after-free vulnerability in Firefox service workers allows attackers to cause crashes or potentially execute arbitrary code.

- **Severity:** Critical 9.8 (`CVSS:3.0/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:** 11 Jun 2018
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-qpcp-783x-fcf2, UBUNTU-CVE-2016-5287

## What is CVE-2016-5287?

CVE-2016-5287 is a critical use after free vulnerability in Mozilla Firefox, published on 11 Jun 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A potentially exploitable use-after-free crash during actor destruction with service workers. This issue does not affect releases earlier than Firefox 49. This vulnerability affects Firefox < 49.0.2.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2016-5287?

It affects 1 product.


Products: Mozilla Firefox.

## How do I fix CVE-2016-5287?

Upgrade to a fixed version.

## Is CVE-2016-5287 being exploited?

There is no known exploitation of CVE-2016-5287 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-2016-5287 and fix it if it is affected.

What it is: CVE-2016-5287 is a critical use after free vulnerability in Mozilla Firefox, published on 11 Jun 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2016-5287 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-2016-5287/ (Markdown: https://insights.sbomify.com/CVE-2016-5287/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-5287
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-5287
- OSV: https://osv.dev/vulnerability/CVE-2016-5287

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-5287/
Summaries are generated and may contain mistakes; the official description above is the record.