Issued at: 2026-09-09
Updated at: 2026-09-10
Advisory content derived from Red Hat RHSA-2026:65159, © Red Hat, Inc., used under CC BY 4.0, with modifications.
Synopsis
Important: thunderbird security update
Description
Mozilla Thunderbird is a standalone mail and newsgroup client.
Security Fix(es):
* firefox: thunderbird: Site isolation issue in the Graphics: CanvasWebGL component (CVE-2026-74934)
* firefox: thunderbird: Privilege escalation in the Networking: Cookies component (CVE-2026-74953)
* firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154 (CVE-2026-74987)
* firefox: thunderbird: Information disclosure in the Graphics component (CVE-2026-74948)
* firefox: thunderbird: Information disclosure in the DOM: UI Events & Focus Handling component (CVE-2026-74971)
* firefox: Race condition, use-after-free in the Graphics component (CVE-2026-74973)
* firefox: thunderbird: Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154 (CVE-2026-74990)
* firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-74936)
* firefox: thunderbird: Site isolation issue in the WebExtensions component (CVE-2026-74960)
* firefox: thunderbird: Mitigation bypass in the Storage: Cache API component (CVE-2026-74959)
* firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-74976)
* firefox: thunderbird: Same-origin policy bypass in the Graphics: ImageLib component (CVE-2026-74974)
* firefox: thunderbird: Mitigation bypass in the Safe Browsing component (CVE-2026-74957)
* firefox: Privilege escalation in the Remote Settings Client component (CVE-2026-74942)
* firefox: thunderbird: Privilege escalation in the DOM: Navigation component (CVE-2026-74939)
* firefox: thunderbird: Information disclosure in the DOM: Push Subscriptions component (CVE-2026-74972)
* firefox: thunderbird: Information disclosure in the Graphics: Text component (CVE-2026-74945)
* firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component (CVE-2026-74963)
* firefox: Integer overflow in the Graphics component (CVE-2026-74964)
* firefox: Site isolation issue in the Networking: Cookies component (CVE-2026-74962)
* firefox: thunderbird: Privilege escalation in the DOM: Networking component (CVE-2026-74935)
For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.