Mozilla Thunderbird (cs) 154.0
Mozilla Thunderbird (cs) 154.0, released August 18, 2026, fixes 56 CVEs in Mozilla Thunderbird (cs). None of them is reported as exploited. Patch Radar priority: Urgent. The latest Mozilla Thunderbird (cs) is 159.0, which also fixes every one of these CVEs.
Superseded. The latest Mozilla Thunderbird (cs) is 159.0, which also fixes every CVE on this page. Install that instead.
Priority of the 56 CVEs
Applies to
| Product | Version |
|---|---|
| Mozilla Thunderbird (cs) | 154.0 |
CVEs this fix closes
| Priority | CVE | Title | CVSS | EPSS | Exploitation |
|---|---|---|---|---|---|
| Urgent | CVE-2026-74943 | Use-after-free in the Graphics: ImageLib component | 9.8 | 0.0096 | None reported |
| Urgent | CVE-2026-74964 | Integer overflow in the Graphics component | 9.8 | 0.0060 | None reported |
| Urgent | CVE-2026-74989 | Internally found bugs fixed in Thunderbird 154 | 9.8 | 0.0057 | None reported |
| Urgent | CVE-2026-74986 | Site isolation issue in the CSS Parsing and Computation component | 9.1 | 0.0056 | None reported |
| Urgent | CVE-2026-74985 | Privilege escalation in the Enterprise Policies component | 9.8 | 0.0053 | None reported |
| Urgent | CVE-2026-74956 | Same-origin policy bypass in the DOM: Service Workers component | 9.1 | 0.0050 | None reported |
| Urgent | CVE-2026-75874 | Sandbox escape in the Remote Settings Client component | 10.0 | 0.0046 | None reported |
| Urgent | CVE-2026-74961 | Side-channel in the Web Audio component | 9.1 | 0.0044 | None reported |
| Urgent | CVE-2026-74940 | Use-after-free in the Graphics: Text component | 9.8 | 0.0041 | None reported |
| Urgent | CVE-2026-74936 | Use-after-free in the JavaScript: WebAssembly component | 9.8 | 0.0040 | None reported |
| Urgent | CVE-2026-74944 | Use-after-free in the DOM: Core & HTML component | 9.8 | 0.0040 | None reported |
| Urgent | CVE-2026-74959 | Mitigation bypass in the Storage: Cache API component | 9.1 | 0.0034 | None reported |
| Urgent | CVE-2026-74979 | Mitigation bypass in the Add-ons Manager component | 9.8 | 0.0031 | None reported |
| High | CVE-2026-74945 | Information disclosure in the Graphics: Text component | 7.5 | 0.0071 | None reported |
| High | CVE-2026-74988 | Internally found bugs fixed in Thunderbird ESR 153.1 and Thunderbird 154 | 9.8 | 0.0061 | None reported |
| High | CVE-2026-74977 | Integer overflow in the Graphics component | 7.5 | 0.0060 | None reported |
| High | CVE-2026-74990 | Internally found bugs fixed in Thunderbird ESR 140.14, Thunderbird ESR 153.1 and Thunderbird 154 | 9.8 | 0.0053 | None reported |
| High | CVE-2026-74982 | Denial-of-service in the Widget component | 7.5 | 0.0053 | None reported |
| High | CVE-2026-74987 | Internally found bugs fixed in Thunderbird ESR 140.14, Thunderbird ESR 153.1 and Thunderbird 154 | 9.8 | 0.0052 | None reported |
| High | CVE-2026-74958 | Information disclosure in the WebRTC component | 7.5 | 0.0045 | None reported |
| High | CVE-2026-74947 | Privilege escalation due to invalid pointer in the Graphics component | 8.8 | 0.0045 | None reported |
| High | CVE-2026-74938 | Mitigation bypass in the JavaScript: GC component | 9.1 | 0.0044 | None reported |
| High | CVE-2026-74954 | Information disclosure due to side-channel in the Storage: Cache API component | 7.5 | 0.0044 | None reported |
| High | CVE-2026-74966 | Information disclosure in the Form Autofill component | 7.5 | 0.0044 | None reported |
| High | CVE-2026-74937 | Use-after-free in the JavaScript: GC component | 8.8 | 0.0044 | None reported |
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