# Mozilla Thunderbird (en-US) 149.0

Mozilla Thunderbird (en-US) 149.0, released March 24, 2026, fixes 14 CVEs in Mozilla Thunderbird (en-US). None of them is reported as exploited. Patch Radar priority: Urgent. The latest Mozilla Thunderbird (en-US) is 159.0, which also fixes every one of these CVEs.

- Web page: https://patchblox.com/security/fix/windows-app/mozilla.thunderbird-149.0
- Platform: Windows apps
- Released: Mar 24, 2026
- Priority: Urgent (Closes CVE-2026-4724, rated Critical)
- CVEs: 14, exploited: 0, on CISA KEV: 0
- Superseded by: [Mozilla Thunderbird (en-US) 159.0](https://patchblox.com/security/data/product/windows-app/mozilla-thunderbird-en-us.md), the latest version, which also fixes every CVE listed here

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Mozilla Thunderbird (en-US)](https://patchblox.com/security/data/product/windows-app/mozilla-thunderbird-en-us.md) |  | 149.0 |

## CVEs this fix closes

| CVE | Priority | Title | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2026-4724](https://patchblox.com/security/data/cve/CVE-2026-4724.md) | Urgent | Undefined behavior in the Audio/Video component | 9.1 | 0.0051 |  |
| [CVE-2026-4729](https://patchblox.com/security/data/cve/CVE-2026-4729.md) | Urgent | Memory safety bugs fixed in Firefox 149 and Thunderbird 149 | 9.8 | 0.0034 |  |
| [CVE-2026-4694](https://patchblox.com/security/data/cve/CVE-2026-4694.md) | High | Incorrect boundary conditions, integer overflow in the Graphics component | 8.2 | 0.0080 |  |
| [CVE-2026-4689](https://patchblox.com/security/data/cve/CVE-2026-4689.md) | High | Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component | 10.0 | 0.0069 |  |
| [CVE-2026-4726](https://patchblox.com/security/data/cve/CVE-2026-4726.md) | High | Denial-of-service in the XML component | 7.5 | 0.0055 |  |
| [CVE-2026-4727](https://patchblox.com/security/data/cve/CVE-2026-4727.md) | High | Denial-of-service in the Libraries component in NSS | 7.5 | 0.0055 |  |
| [CVE-2026-4692](https://patchblox.com/security/data/cve/CVE-2026-4692.md) | High | Sandbox escape in the Responsive Design Mode component | 10.0 | 0.0051 |  |
| [CVE-2026-4718](https://patchblox.com/security/data/cve/CVE-2026-4718.md) | High | Undefined behavior in the WebRTC: Signaling component | 8.2 | 0.0048 |  |
| [CVE-2026-4720](https://patchblox.com/security/data/cve/CVE-2026-4720.md) | High | Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149 | 9.8 | 0.0044 |  |
| [CVE-2026-4721](https://patchblox.com/security/data/cve/CVE-2026-4721.md) | High | Memory safety bugs fixed in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149 | 9.8 | 0.0044 |  |
| [CVE-2026-4710](https://patchblox.com/security/data/cve/CVE-2026-4710.md) | High | Incorrect boundary conditions in the Audio/Video component | 9.8 | 0.0043 |  |
| [CVE-2026-4371](https://patchblox.com/security/data/cve/CVE-2026-4371.md) | High | Out of bounds read in IMAP parsing | 8.2 | 0.0037 |  |
| [CVE-2026-3889](https://patchblox.com/security/data/cve/CVE-2026-3889.md) | High | Spoofing issue in Thunderbird | 8.2 | 0.0021 |  |
| [CVE-2026-4728](https://patchblox.com/security/data/cve/CVE-2026-4728.md) | Routine | Spoofing issue in the Privacy: Anti-Tracking component | 6.5 | 0.0024 |  |

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Data as of 2026-11-08T19:12:23Z 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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