# CVE-2023-25743: Security feature bypass in Firefox

> Attackers can spoof browser chrome in Firefox Focus by exploiting missing fullscreen notifications, potentially misleading users about the active page.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/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:** 2 Jun 2023
- **Updated:** 9 Jan 2025
- **Also known as:** GHSA-j7hq-xhjg-3w36

## What is CVE-2023-25743?

CVE-2023-25743 is a high-severity vulnerability in Mozilla Firefox, published on 2 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A lack of in app notification for entering fullscreen mode could have lead to a malicious website spoofing browser chrome.<br>*This bug only affects Firefox Focus. Other versions of Firefox are unaffected.*. This vulnerability affects Firefox < 110 and Firefox ESR < 102.8.

Weakness: CWE-290 (Authentication Bypass by Spoofing)

## Which versions are affected by CVE-2023-25743?

It affects 1 product.


Products: Mozilla Firefox Focus.

## How do I fix CVE-2023-25743?

Upgrade to a fixed version.

## Is CVE-2023-25743 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-25743 exists.

## Other vulnerabilities in Mozilla Firefox

- [CVE-2024-10474](https://insights.sbomify.com/CVE-2024-10474/): Security feature bypass in Focus for iOS (critical 9.1)
- [CVE-2023-29534](https://insights.sbomify.com/CVE-2023-29534/): Security feature bypass in Firefox for Android (critical 9.1)
- [CVE-2024-1563](https://insights.sbomify.com/CVE-2024-1563/): Race condition in Focus for iOS (high 8.1)
- [CVE-2024-0605](https://insights.sbomify.com/CVE-2024-0605/): Race condition in Focus for iOS (high 7.5)
- [CVE-2025-10290](https://insights.sbomify.com/CVE-2025-10290/): Other in Focus for iOS (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-25743 and fix it if it is affected.

What it is: CVE-2023-25743 is a high-severity vulnerability in Mozilla Firefox, published on 2 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-25743 exists.

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-2023-25743/ (Markdown: https://insights.sbomify.com/CVE-2023-25743/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-25743
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-25743
- OSV: https://osv.dev/vulnerability/CVE-2023-25743

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-25743/
Summaries are generated and may contain mistakes; the official description above is the record.