# CVE-2014-8639: Auth bypass in n/a

> Remote HTTP proxy servers can conduct session fixation attacks in Firefox by manipulating Set-Cookie headers in 407 responses, potentially leading to account takeover.

- **Severity:** Medium 6.8 (`AV:N/AC:M/Au:N/C:P/I:P/A:P`)
- **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:** 14 Jan 2015
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-cfgr-xpqw-rcxf, UBUNTU-CVE-2014-8639

## What is CVE-2014-8639?

CVE-2014-8639 is a medium-severity authentication bypass vulnerability in Mozilla Firefox, published on 14 Jan 2015. 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

Mozilla Firefox before 35.0, Firefox ESR 31.x before 31.4, Thunderbird before 31.4, and SeaMonkey before 2.32 do not properly interpret Set-Cookie headers within responses that have a 407 (aka Proxy Authentication Required) status code, which allows remote HTTP proxy servers to conduct session fixation attacks by providing a cookie name that corresponds to the session cookie of the origin server.

## Which versions are affected by CVE-2014-8639?

It affects 4 products.


Products: Mozilla Firefox, Mozilla Firefox Esr, Mozilla Seamonkey, Mozilla Thunderbird.

## How do I fix CVE-2014-8639?

Upgrade to a fixed version.

## Is CVE-2014-8639 being exploited?

There is no known exploitation of CVE-2014-8639 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-2014-8639 and fix it if it is affected.

What it is: CVE-2014-8639 is a medium-severity authentication bypass vulnerability in Mozilla Firefox, published on 14 Jan 2015. 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-2014-8639 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-2014-8639/ (Markdown: https://insights.sbomify.com/CVE-2014-8639/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2014-8639
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2014-8639
- OSV: https://osv.dev/vulnerability/CVE-2014-8639

---
From sbomify Insights: https://insights.sbomify.com/CVE-2014-8639/
Summaries are generated and may contain mistakes; the official description above is the record.