Mozilla Thunderbird Security Advisory 2026-80: Multiple High Severity Vulns (UAF/Privesc/CanvasWebGL)

Mozilla Foundation Security Advisory 2026-80 Vulnerability Overview Publication Date: August 18, 2026 Impact: High Product: Thunderbird Fixed Version: Thunderbird 153.1 Scope of Impact These vulnerabilities cannot be exploited via email in Thunderbird because scripts are disabled when reading emails; however, risks may exist in the browser or similar contexts. Remediation Upgrade to Thunderbird version 153.1. Vulnerability Details CVE-2026-74934: Site isolation issue in the Graphics: CanvasWebGL component Reporter: satyamasd Impact: high References: Bug 2050594 CVE-2026-74935: Privilege escalation in the DOM: Networking component Reporter: Yaqoub Aldurayhim Impact: high References: Bug 2051013 CVE-2026-74936: Use-after-free in the JavaScript: WebAssembly component Reporter: Amy Burnett of OpenAI Impact: high References: Bug 2052088 CVE-2026-74937: Use-after-free in the JavaScript: GC component Reporter: Amy Burnett of OpenAI Impact: high References: Bug 2053337 CVE-2026-74938: Mitigation bypass in the JavaScript: GC component Reporter: Amy Burnett of OpenAI Impact: high References: Bug 2053688 CVE-2026-74939: Privilege escalation in the DOM: Navigation component Reporter: choeseyeong Impact: high References: Bug 2054416 CVE-2026-74940: Use-after-free in the Graphics: Text component Reporter: kiyong Impact: high References: Bug 2054642 CVE-2026-74941: Privilege escalation in the Graphics: CanvasWebGL component Reporter: Jacolon Walker Impact: high References: Bug 2055056 CVE-2026-74942: Privilege escalation in the Remote Settings Client component Reporter: Gal Ankonina Impact: high References: Bug 2056571 CVE-2026-74943: Use-after-free in the Graphics: ImageLib component Reporter: Abdulaziz Alasaqah Impact: high References: Bug 2057308 CVE-2026-74944: Use-after-free in the DOM: Core & HTML component Reporter: Amy Burnett of OpenAI Impact: high References: Bug 2057778 CVE-2026-74945: Information disclosure in the Graphics: Text component Reporter: Abdulaziz Alasaqah Impact: high References: Bug 2057808 CVE-2026-74946: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component Reporter: locust1b Impact: high References: Bug 2059997 CVE-2026-74947: Privilege escalation due to invalid pointer in the Graphics component Reporter: navapon Impact: high References: Bug 2060210 CVE-2026-74948: Information disclosure in the Graphics component Reporter: Yaqoub Aldurayhim Impact: high References: Bug 2060106 CVE-2026-74949: Privilege escalation due to use-after-free in the Graphics: Canvas2D component Reporter: r00tdaddy Impact: high References: Bug 2060249 CVE-2026-74950: Privilege escalation in the Downloads API component Reporter: Frederik Braun Impact: moderate References: Bug 1880253 CVE-2026-74953: Privilege escalation in the Networking: Cookies component Reporter: Satoki Tsuji Impact: moderate References: Bug 2022392 CVE-2026-74954: Information disclosure due to side-channel in the Storage: Cache API component Reporter: Tomoya Nakanishi Impact: moderate References: Bug 2020732 CVE-2026-74955: Privilege escalation in the Request Handling component Reporter: jmwebdevelopement Impact: moderate References: Bug 2029205 CVE-2026-74956: Same-origin policy bypass in the DOM: Service Workers component Reporter: pakhtunov.anton.n Impact: moderate References: Bug 2032406 CVE-2026-74957: Mitigation bypass in the Safe Browsing component Reporter: Tomoya Nakanishi Impact: moderate References: Bug 2041900 CVE-2026-74958: Information disclosure in the WebRTC component Reporter: Tomoya Nakanishi Impact: moderate References: Bug 2045308 CVE-2026-74959: Mitigation bypass in the Storage: Cache API component Reporter: David Bors at Snyk Security Labs Impact: moderate References: Bug 2047053 CVE-2026-74960: Site isolation issue in the WebExtensions component Reporter: Khanh Nguyen Impact: moderate References: Bug 2049148 CVE-2026-74961: Side-channel in the Web Audio component Reporter: Rintaro Kawasugi Impact: moderate References: Bug 2050380 CVE-2026-74962: Site isolation issue in the Networking: Cookies component Reporter: Yaqoub Aldurayhim Impact: moderate References: Bug 2050425 CVE-2026-74963: Same-origin policy bypass in the Networking: Cookies component Reporter: 5up3rh31 Impact: moderate References: Bug 2050482 CVE-2026-74964: Integer overflow in the Graphics component Reporter: 5up3rh31 Impact: moderate References: Bug 2053327 CVE-2026-74965: Privilege escalation in the Shell Integration component Reporter: Khanh Nguyen Impact: moderate References: Bug 2053455 CVE-2026-74966: Information disclosure in the Form Autofill component Reporter: Khanh Nguyen Impact: moderate References: Bug 2053455

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Mozilla Thunderbird Security Advisory 2026-80: Multiple High Severity Vulns (UAF/Privesc/CanvasWebGL)