# CVE-2018-18506: Server-side request forgery in Firefox

> Attackers can route localhost requests through a proxy via PAC files, potentially exposing local services when proxy auto-detection is enabled.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 Feb 2019
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-18506, GHSA-4gc3-hqxg-hgp9, UBUNTU-CVE-2018-18506

## What is CVE-2018-18506?

CVE-2018-18506 is a medium-severity server-side request forgery vulnerability in Canonical Ubuntu Linux, published on 5 Feb 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

When proxy auto-detection is enabled, if a web server serves a Proxy Auto-Configuration (PAC) file or if a PAC file is loaded locally, this PAC file can specify that requests to the localhost are to be sent through the proxy to another server. This behavior is disallowed by default when a proxy is manually configured, but when enabled could allow for attacks on services and tools that bind to the localhost for networked behavior if they are accessed through browsing. This vulnerability affects Firefox < 65.

## Which versions are affected by CVE-2018-18506?

It affects 12 products.


Products: Canonical Ubuntu Linux, Debian Debian Linux, Mozilla Firefox, Opensuse Leap, Redhat Enterprise Linux, Redhat Enterprise Linux Desktop, Redhat Enterprise Linux Eus, 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-2018-18506?

Upgrade to a fixed version.

## Is CVE-2018-18506 being exploited?

There is no known exploitation of CVE-2018-18506 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-18506 and fix it if it is affected.

What it is: CVE-2018-18506 is a medium-severity server-side request forgery vulnerability in Canonical Ubuntu Linux, published on 5 Feb 2019. 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-2018-18506 in the wild and no public exploit code.

Affected product: Canonical Ubuntu 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-2018-18506/ (Markdown: https://insights.sbomify.com/CVE-2018-18506/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-18506
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-18506
- OSV: https://osv.dev/vulnerability/CVE-2018-18506

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-18506/
Summaries are generated and may contain mistakes; the official description above is the record.