# Firefox Developer Edition (en-US) 134.0

Firefox Developer Edition (en-US) 134.0, released December 13, 2024, fixes 9 CVEs in Firefox Developer Edition (en-US). None of them is reported as exploited. Patch Radar priority: High. The latest Firefox Developer Edition (en-US) is 156.0, which also fixes every one of these CVEs.

- Web page: https://patchblox.com/security/fix/windows-app/mozilla.firefox.developeredition-134.0
- Platform: Windows apps
- Released: Dec 13, 2024
- Priority: High (Closes CVE-2025-0242, high severity)
- CVEs: 9, exploited: 0, on CISA KEV: 0
- Superseded by: [Firefox Developer Edition (en-US) 156.0](https://patchblox.com/security/data/product/windows-app/firefox-developer-edition-en-us.md), the latest version, which also fixes every CVE listed here

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Firefox Developer Edition (en-US)](https://patchblox.com/security/data/product/windows-app/firefox-developer-edition-en-us.md) |  | 134.0 |

## CVEs this fix closes

| CVE | Priority | Title | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2025-0242](https://patchblox.com/security/data/cve/CVE-2025-0242.md) | High | Memory safety bugs fixed in Firefox 134, Thunderbird 134, Firefox ESR 115.19, Firefox ESR 128.6, Thunderbird 115.19, and Thunderbird 128.6 | 8.8 | 0.1472 |  |
| [CVE-2025-0247](https://patchblox.com/security/data/cve/CVE-2025-0247.md) | High | Memory safety bugs fixed in Firefox 134 and Thunderbird 134 | 9.8 | 0.1061 |  |
| [CVE-2025-0241](https://patchblox.com/security/data/cve/CVE-2025-0241.md) | High | Memory corruption when using JavaScript Text Segmentation | 7.7 | 0.0073 |  |
| [CVE-2025-0244](https://patchblox.com/security/data/cve/CVE-2025-0244.md) | Routine | Address bar spoofing using an invalid protocol scheme on Firefox for Android | 5.3 | 0.0739 |  |
| [CVE-2025-0238](https://patchblox.com/security/data/cve/CVE-2025-0238.md) | Routine | Use-after-free when breaking lines in text | 6.5 | 0.0079 |  |
| [CVE-2025-0240](https://patchblox.com/security/data/cve/CVE-2025-0240.md) | Routine | Compartment mismatch when parsing JavaScript JSON module | 6.5 | 0.0067 |  |
| [CVE-2025-0237](https://patchblox.com/security/data/cve/CVE-2025-0237.md) | Routine | WebChannel APIs susceptible to confused deputy attack | 6.8 | 0.0060 |  |
| [CVE-2025-0245](https://patchblox.com/security/data/cve/CVE-2025-0245.md) | Routine | Lock screen setting bypass in Firefox Focus for Android | 3.3 | 0.0029 |  |
| [CVE-2025-0239](https://patchblox.com/security/data/cve/CVE-2025-0239.md) | Routine | Alt-Svc ALPN validation failure when redirected | 5.4 | 0.0023 |  |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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