# CVE-2018-5163: Privilege escalation in Firefox

> Attackers with content process control can replace cached bytecode to execute code with parent process privileges, escaping the sandbox.

- **Severity:** High 8.1 (`CVSS:3.0/AV:N/AC:H/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:** 5 Aug 2024
- **Also known as:** GHSA-647q-gc86-99gj, UBUNTU-CVE-2018-5163

## What is CVE-2018-5163?

CVE-2018-5163 is a high-severity vulnerability in Canonical Ubuntu Linux, published on 11 Jun 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

If a malicious attacker has used another vulnerability to gain full control over a content process, they may be able to replace the alternate data resources stored in the JavaScript Start-up Bytecode Cache (JSBC) for other JavaScript code. If the parent process then runs this replaced code, the executed script would be run with the parent process' privileges, escaping the sandbox on content processes. This vulnerability affects Firefox < 60.

Weakness: CWE-281 (Improper Preservation of Permissions)

## Which versions are affected by CVE-2018-5163?

It affects 2 products.


Products: Canonical Ubuntu Linux, Mozilla Firefox.

## How do I fix CVE-2018-5163?

Upgrade to a fixed version.

## Is CVE-2018-5163 being exploited?

There is no known exploitation of CVE-2018-5163 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-2018-5163 and fix it if it is affected.

What it is: CVE-2018-5163 is a high-severity vulnerability in Canonical Ubuntu Linux, 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-2018-5163 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-2018-5163/ (Markdown: https://insights.sbomify.com/CVE-2018-5163/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-5163
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-5163
- OSV: https://osv.dev/vulnerability/CVE-2018-5163

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-5163/
Summaries are generated and may contain mistakes; the official description above is the record.