# CVE-2023-29542: Security feature bypass in Firefox

> Attackers can bypass file extension security checks using newlines in filenames, potentially leading to accidental execution of malicious code on Windows.

- **Severity:** Critical 9.8 (`CVSS:3.1/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:** 19 Jun 2023
- **Updated:** 11 Dec 2024
- **Also known as:** GHSA-pc79-pjx7-pq9h, UBUNTU-CVE-2023-29542

## What is CVE-2023-29542?

CVE-2023-29542 is a critical vulnerability in Mozilla Firefox, published on 19 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A newline in a filename could have been used to bypass the file extension security mechanisms that replace malicious file extensions such as .lnk  with .download. This could have led to accidental execution of malicious code.

*This bug only affects Firefox and Thunderbird on Windows. Other versions of Firefox and Thunderbird are unaffected.* This vulnerability affects Firefox < 112, Firefox ESR < 102.10, and Thunderbird < 102.10.

## Which versions are affected by CVE-2023-29542?

It affects 3 products.


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

## How do I fix CVE-2023-29542?

Upgrade to a fixed version.

## Is CVE-2023-29542 being exploited?

There is no known exploitation of CVE-2023-29542 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-2023-29542 and fix it if it is affected.

What it is: CVE-2023-29542 is a critical vulnerability in Mozilla Firefox, published on 19 Jun 2023. 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-2023-29542 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-2023-29542/ (Markdown: https://insights.sbomify.com/CVE-2023-29542/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-29542
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-29542
- OSV: https://osv.dev/vulnerability/CVE-2023-29542

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-29542/
Summaries are generated and may contain mistakes; the official description above is the record.