# Mozilla Thunderbird (de) 154.0 Mozilla Thunderbird (de) 154.0, released August 18, 2026, fixes 56 CVEs in Mozilla Thunderbird (de). None of them is reported as exploited. Patch Radar priority: Urgent. The latest Mozilla Thunderbird (de) is 159.0, which also fixes every one of these CVEs. - Web page: https://patchblox.com/security/fix/windows-app/mozilla.thunderbird.de-154.0 - Platform: Windows apps - Released: Aug 18, 2026 - Priority: Urgent (Closes CVE-2026-74943, rated Critical) - CVEs: 56, exploited: 0, on CISA KEV: 0 - Superseded by: [Mozilla Thunderbird (de) 159.0](https://patchblox.com/security/data/product/windows-app/mozilla-thunderbird-de.md), the latest version, which also fixes every CVE listed here ## Applies to | Product | Release | Fixed in | |---|---|---| | [Mozilla Thunderbird (de)](https://patchblox.com/security/data/product/windows-app/mozilla-thunderbird-de.md) | | 154.0 | ## CVEs this fix closes | CVE | Priority | Title | CVSS | EPSS | Exploitation | |---|---|---|---:|---:|---| | [CVE-2026-74943](https://patchblox.com/security/data/cve/CVE-2026-74943.md) | Urgent | Use-after-free in the Graphics: ImageLib component | 9.8 | 0.0096 | | | [CVE-2026-74964](https://patchblox.com/security/data/cve/CVE-2026-74964.md) | Urgent | Integer overflow in the Graphics component | 9.8 | 0.0060 | | | [CVE-2026-74989](https://patchblox.com/security/data/cve/CVE-2026-74989.md) | Urgent | Internally found bugs fixed in Thunderbird 154 | 9.8 | 0.0057 | | | [CVE-2026-74986](https://patchblox.com/security/data/cve/CVE-2026-74986.md) | Urgent | Site isolation issue in the CSS Parsing and Computation component | 9.1 | 0.0056 | | | [CVE-2026-74985](https://patchblox.com/security/data/cve/CVE-2026-74985.md) | Urgent | Privilege escalation in the Enterprise Policies component | 9.8 | 0.0053 | | | [CVE-2026-74956](https://patchblox.com/security/data/cve/CVE-2026-74956.md) | Urgent | Same-origin policy bypass in the DOM: Service Workers component | 9.1 | 0.0050 | | | [CVE-2026-75874](https://patchblox.com/security/data/cve/CVE-2026-75874.md) | Urgent | Sandbox escape in the Remote Settings Client component | 10.0 | 0.0046 | | | [CVE-2026-74961](https://patchblox.com/security/data/cve/CVE-2026-74961.md) | Urgent | Side-channel in the Web Audio component | 9.1 | 0.0044 | | | [CVE-2026-74940](https://patchblox.com/security/data/cve/CVE-2026-74940.md) | Urgent | Use-after-free in the Graphics: Text component | 9.8 | 0.0041 | | | [CVE-2026-74936](https://patchblox.com/security/data/cve/CVE-2026-74936.md) | Urgent | Use-after-free in the JavaScript: WebAssembly component | 9.8 | 0.0040 | | | [CVE-2026-74944](https://patchblox.com/security/data/cve/CVE-2026-74944.md) | Urgent | Use-after-free in the DOM: Core & HTML component | 9.8 | 0.0040 | | | [CVE-2026-74959](https://patchblox.com/security/data/cve/CVE-2026-74959.md) | Urgent | Mitigation bypass in the Storage: Cache API component | 9.1 | 0.0034 | | | [CVE-2026-74979](https://patchblox.com/security/data/cve/CVE-2026-74979.md) | Urgent | Mitigation bypass in the Add-ons Manager component | 9.8 | 0.0031 | | | [CVE-2026-74945](https://patchblox.com/security/data/cve/CVE-2026-74945.md) | High | Information disclosure in the Graphics: Text component | 7.5 | 0.0071 | | | [CVE-2026-74988](https://patchblox.com/security/data/cve/CVE-2026-74988.md) | High | Internally found bugs fixed in Thunderbird ESR 153.1 and Thunderbird 154 | 9.8 | 0.0061 | | | [CVE-2026-74977](https://patchblox.com/security/data/cve/CVE-2026-74977.md) | High | Integer overflow in the Graphics component | 7.5 | 0.0060 | | | [CVE-2026-74990](https://patchblox.com/security/data/cve/CVE-2026-74990.md) | High | Internally found bugs fixed in Thunderbird ESR 140.14, Thunderbird ESR 153.1 and Thunderbird 154 | 9.8 | 0.0053 | | | [CVE-2026-74982](https://patchblox.com/security/data/cve/CVE-2026-74982.md) | High | Denial-of-service in the Widget component | 7.5 | 0.0053 | | | [CVE-2026-74987](https://patchblox.com/security/data/cve/CVE-2026-74987.md) | High | Internally found bugs fixed in Thunderbird ESR 140.14, Thunderbird ESR 153.1 and Thunderbird 154 | 9.8 | 0.0052 | | | [CVE-2026-74958](https://patchblox.com/security/data/cve/CVE-2026-74958.md) | High | Information disclosure in the WebRTC component | 7.5 | 0.0045 | | | [CVE-2026-74947](https://patchblox.com/security/data/cve/CVE-2026-74947.md) | High | Privilege escalation due to invalid pointer in the Graphics component | 8.8 | 0.0045 | | | [CVE-2026-74938](https://patchblox.com/security/data/cve/CVE-2026-74938.md) | High | Mitigation bypass in the JavaScript: GC component | 9.1 | 0.0044 | | | [CVE-2026-74954](https://patchblox.com/security/data/cve/CVE-2026-74954.md) | High | Information disclosure due to side-channel in the Storage: Cache API component | 7.5 | 0.0044 | | | [CVE-2026-74966](https://patchblox.com/security/data/cve/CVE-2026-74966.md) | High | Information disclosure in the Form Autofill component | 7.5 | 0.0044 | | | [CVE-2026-74937](https://patchblox.com/security/data/cve/CVE-2026-74937.md) | High | Use-after-free in the JavaScript: GC component | 8.8 | 0.0044 | | | [CVE-2026-74950](https://patchblox.com/security/data/cve/CVE-2026-74950.md) | High | Privilege escalation in the Downloads API component | 8.8 | 0.0042 | | | [CVE-2026-74952](https://patchblox.com/security/data/cve/CVE-2026-74952.md) | High | Privilege escalation in the Application Update component | 8.8 | 0.0042 | | | [CVE-2026-74955](https://patchblox.com/security/data/cve/CVE-2026-74955.md) | High | Privilege escalation in the Request Handling component | 8.8 | 0.0042 | | | [CVE-2026-74969](https://patchblox.com/security/data/cve/CVE-2026-74969.md) | High | Use-after-free in the Layout: Text and Fonts component | 8.8 | 0.0040 | | | [CVE-2026-74978](https://patchblox.com/security/data/cve/CVE-2026-74978.md) | High | Clickjacking issue in the Widget component | 8.1 | 0.0038 | | | [CVE-2026-74946](https://patchblox.com/security/data/cve/CVE-2026-74946.md) | High | Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component | 8.8 | 0.0033 | | | [CVE-2026-74983](https://patchblox.com/security/data/cve/CVE-2026-74983.md) | High | Mitigation bypass in the Data Loss Prevention component | 8.1 | 0.0033 | | | [CVE-2026-74971](https://patchblox.com/security/data/cve/CVE-2026-74971.md) | High | Information disclosure in the DOM: UI Events & Focus Handling component | 7.5 | 0.0032 | | | [CVE-2026-74941](https://patchblox.com/security/data/cve/CVE-2026-74941.md) | High | Privilege escalation in the Graphics: CanvasWebGL component | 8.8 | 0.0032 | | | [CVE-2026-74976](https://patchblox.com/security/data/cve/CVE-2026-74976.md) | High | JIT miscompilation in the JavaScript Engine: JIT component | 7.5 | 0.0032 | | | [CVE-2026-74949](https://patchblox.com/security/data/cve/CVE-2026-74949.md) | High | Privilege escalation due to use-after-free in the Graphics: Canvas2D component | 8.8 | 0.0032 | | | [CVE-2026-74948](https://patchblox.com/security/data/cve/CVE-2026-74948.md) | High | Information disclosure in the Graphics component | 7.5 | 0.0031 | | | [CVE-2026-74935](https://patchblox.com/security/data/cve/CVE-2026-74935.md) | High | Privilege escalation in the DOM: Networking component | 8.8 | 0.0031 | | | [CVE-2026-74939](https://patchblox.com/security/data/cve/CVE-2026-74939.md) | High | Privilege escalation in the DOM: Navigation component | 8.8 | 0.0030 | | | [CVE-2026-74942](https://patchblox.com/security/data/cve/CVE-2026-74942.md) | High | Privilege escalation in the Remote Settings Client component | 8.8 | 0.0030 | | | [CVE-2026-74965](https://patchblox.com/security/data/cve/CVE-2026-74965.md) | High | Privilege escalation in the Shell Integration component | 8.8 | 0.0030 | | | [CVE-2026-74957](https://patchblox.com/security/data/cve/CVE-2026-74957.md) | High | Mitigation bypass in the Safe Browsing component | 8.1 | 0.0030 | | | [CVE-2026-74953](https://patchblox.com/security/data/cve/CVE-2026-74953.md) | High | Privilege escalation in the Networking: Cookies component | 8.8 | 0.0030 | | | [CVE-2026-74972](https://patchblox.com/security/data/cve/CVE-2026-74972.md) | High | Information disclosure in the DOM: Push Subscriptions component | 7.5 | 0.0026 | | | [CVE-2026-100832](https://patchblox.com/security/data/cve/CVE-2026-100832.md) | High | Use-after-free in the Graphics: Canvas2D component | 8.8 | 0.0025 | | | [CVE-2026-74981](https://patchblox.com/security/data/cve/CVE-2026-74981.md) | High | Site isolation issue in the Audio/Video: Web Codecs component | 8.1 | 0.0021 | | | [CVE-2026-74973](https://patchblox.com/security/data/cve/CVE-2026-74973.md) | High | Race condition, use-after-free in the Graphics component | 7.5 | 0.0018 | | | [CVE-2026-74960](https://patchblox.com/security/data/cve/CVE-2026-74960.md) | High | Site isolation issue in the WebExtensions component | 8.1 | 0.0016 | | | [CVE-2026-74962](https://patchblox.com/security/data/cve/CVE-2026-74962.md) | High | Site isolation issue in the Networking: Cookies component | 8.1 | 0.0016 | | | [CVE-2026-74934](https://patchblox.com/security/data/cve/CVE-2026-74934.md) | High | Site isolation issue in the Graphics: CanvasWebGL component | 7.5 | 0.0016 | | | [CVE-2026-74974](https://patchblox.com/security/data/cve/CVE-2026-74974.md) | High | Same-origin policy bypass in the Graphics: ImageLib component | 7.5 | 0.0014 | | | [CVE-2026-74963](https://patchblox.com/security/data/cve/CVE-2026-74963.md) | High | Same-origin policy bypass in the Networking: Cookies component | 7.5 | 0.0012 | | | [CVE-2026-74967](https://patchblox.com/security/data/cve/CVE-2026-74967.md) | High | Same-origin policy bypass in the Audio/Video: Playback component | 7.5 | 0.0012 | | | [CVE-2026-74984](https://patchblox.com/security/data/cve/CVE-2026-74984.md) | Routine | Race condition in the JavaScript Engine component | 6.8 | 0.0028 | | | [CVE-2026-74968](https://patchblox.com/security/data/cve/CVE-2026-74968.md) | Routine | Site isolation issue in the Graphics: WebRender component | 5.4 | 0.0016 | | | [CVE-2026-74970](https://patchblox.com/security/data/cve/CVE-2026-74970.md) | Routine | Site isolation issue in the Graphics component | 5.4 | 0.0016 | | --- Data as of 2026-11-09T19:38:12Z 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 Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.