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.
Superseded. The latest Mozilla Thunderbird (en-US) is 159.0, which also fixes every CVE on this page. Install that instead.
Priority of the 14 CVEs
Applies to
| Product | Version |
|---|---|
| Mozilla Thunderbird (en-US) | 149.0 |
CVEs this fix closes
| Priority | CVE | Title | CVSS | EPSS | Exploitation |
|---|---|---|---|---|---|
| Urgent | CVE-2026-4724 | Undefined behavior in the Audio/Video component | 9.1 | 0.0051 | None reported |
| Urgent | CVE-2026-4729 | Memory safety bugs fixed in Firefox 149 and Thunderbird 149 | 9.8 | 0.0034 | None reported |
| High | CVE-2026-4694 | Incorrect boundary conditions, integer overflow in the Graphics component | 8.2 | 0.0080 | None reported |
| High | CVE-2026-4689 | Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component | 10.0 | 0.0069 | None reported |
| High | CVE-2026-4726 | Denial-of-service in the XML component | 7.5 | 0.0055 | None reported |
| High | CVE-2026-4727 | Denial-of-service in the Libraries component in NSS | 7.5 | 0.0055 | None reported |
| High | CVE-2026-4692 | Sandbox escape in the Responsive Design Mode component | 10.0 | 0.0051 | None reported |
| High | CVE-2026-4718 | Undefined behavior in the WebRTC: Signaling component | 8.2 | 0.0048 | None reported |
| High | CVE-2026-4720 | Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149 | 9.8 | 0.0044 | None reported |
| High | CVE-2026-4721 | 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 | None reported |
| High | CVE-2026-4710 | Incorrect boundary conditions in the Audio/Video component | 9.8 | 0.0043 | None reported |
| High | CVE-2026-4371 | Out of bounds read in IMAP parsing | 8.2 | 0.0037 | None reported |
| High | CVE-2026-3889 | Spoofing issue in Thunderbird | 8.2 | 0.0021 | None reported |
| Routine | CVE-2026-4728 | Spoofing issue in the Privacy: Anti-Tracking component | 6.5 | 0.0024 | None reported |
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