Thunderbird vulnerabilities

801 known vulnerabilities in Thunderbird from Mozilla. 800 are rated high or critical, and 14 have been exploited in real attacks. Each entry lists the affected versions and the release that fixes it, where the vendor has published one.

801vulnerabilities

229critical

571high

14exploited

8.7average CVSS score

Latest first

8.8 High severity
Firefox: Improper Privilege Management
CVE-2026-109756Oct 13, 2026Mozilla
Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.1 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-109754Oct 13, 2026Mozilla
Incorrect boundary conditions in the DOM: Editor component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.1 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-109753Oct 13, 2026Mozilla
Incorrect boundary conditions in the Layout component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
9.6 Critical severity
Firefox: Use of Uninitialized Resource
CVE-2026-109745Oct 13, 2026Mozilla
Sandbox escape due to uninitialized memory in the DOM: Web Serial component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.8 High severity
Firefox: Improper Privilege Management
CVE-2026-109743Oct 13, 2026Mozilla
Privilege escalation in the Panning and Zooming component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
9.6 Critical severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-109740Oct 13, 2026Mozilla
Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.1 High severity
Firefox: Protection Mechanism Failure
CVE-2026-109737Oct 13, 2026Mozilla
Mitigation bypass in the Enterprise Policies component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.1 High severity
Firefox: User Interface (UI) Misrepresentation of Critical Information
CVE-2026-109736Oct 13, 2026Mozilla
Frame poisoning in the Layout component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, Thunderbird 153.5, and Firefox ESR 115.45.
8.1 High severity
Firefox: Protection Mechanism Failure
CVE-2026-109734Oct 13, 2026Mozilla
Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.1 High severity
Firefox: Access of Resource Using Incompatible Type
CVE-2026-109733Oct 13, 2026Mozilla
JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.8 High severity
Firefox: Integer Overflow or Wraparound
CVE-2026-109730Oct 13, 2026Mozilla
Integer overflow in the Graphics component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.1 High severity
Firefox: Always-Incorrect Control Flow Implementation
CVE-2026-109722Oct 13, 2026Mozilla
JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
7.1 High severity
Firefox: Access of Resource Using Incompatible Type
CVE-2026-109720Oct 13, 2026Mozilla
JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.1 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-109716Oct 13, 2026Mozilla
Incorrect boundary conditions in the JavaScript Engine component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.1 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-109715Oct 13, 2026Mozilla
Incorrect boundary conditions in the JavaScript Engine component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
7.1 High severity
Firefox: Use of Uninitialized Resource
CVE-2026-109712Oct 13, 2026Mozilla
Sandbox escape due to uninitialized memory in the Graphics component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.8 High severity
Firefox: Exposure of Sensitive Information to an Unauthorized Actor
CVE-2026-109709Oct 13, 2026Mozilla
Information disclosure, privilege escalation in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
9.6 Critical severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-109708Oct 13, 2026Mozilla
Sandbox escape due to incorrect boundary conditions in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, Thunderbird 153.5, and Firefox ESR 115.44.
9.6 Critical severity
Firefox: Use After Free
CVE-2026-109707Oct 13, 2026Mozilla
Sandbox escape due to use-after-free in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, Thunderbird 153.5, and Firefox ESR 115.44.
9.6 Critical severity
Firefox: Use After Free
CVE-2026-109705Oct 13, 2026Mozilla
Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, Thunderbird 153.5, and Firefox ESR 115.44.
8.8 High severity
Firefox: Improper Privilege Management
CVE-2026-109704Oct 13, 2026Mozilla
Privilege escalation in the Application Update component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.8 High severity
Firefox: Use After Free
CVE-2026-100832Sep 29, 2026Mozilla
Use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 140.17, Thunderbird 153.4, Firefox ESR 115.42, and Firefox ESR 140.17.
8.8 High severity
Firefox: Use After Free
CVE-2026-100831Sep 29, 2026Mozilla
Use-after-free in the DOM: UI Events & Focus Handling component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
8.1 High severity
Firefox: Origin Validation Error
CVE-2026-100830Sep 29, 2026Mozilla
Mitigation bypass in the DOM: Navigation component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
9.6 Critical severity
Firefox: Protection Mechanism Failure
CVE-2026-100829Sep 29, 2026Mozilla
Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
9.6 Critical severity
Firefox: Protection Mechanism Failure
CVE-2026-100828Sep 29, 2026Mozilla
Mitigation bypass in the Bookmarks & History component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
8.8 High severity
Firefox: Use After Free
CVE-2026-100825Sep 29, 2026Mozilla
Use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
8.8 High severity
Thunderbird: Improper Privilege Management
CVE-2026-100820Sep 29, 2026Mozilla
Privilege escalation in the Address Bar component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.
9.6 Critical severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-100819Sep 29, 2026Mozilla
Sandbox escape due to incorrect boundary conditions in the XPCOM component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
9.6 Critical severity
Thunderbird: Use After Free
CVE-2026-100818Sep 29, 2026Mozilla
Sandbox escape due to use-after-free in the Widget: Gtk component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.
8.1 High severity
Firefox: Origin Validation Error
CVE-2026-100816Sep 29, 2026Mozilla
Site isolation issue in the DOM: Networking component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
8.8 High severity
Firefox: Use After Free
CVE-2026-100815Sep 29, 2026Mozilla
Use-after-free in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
8.8 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-100814Sep 29, 2026Mozilla
Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
9.6 Critical severity
Thunderbird: Use After Free
CVE-2026-100811Sep 29, 2026Mozilla
Sandbox escape due to use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.
8.1 High severity
Firefox: Origin Validation Error
CVE-2026-100809Sep 29, 2026Mozilla
Same-origin policy bypass in the DevTools component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
8.8 High severity
Firefox: Protection Mechanism Failure
CVE-2026-100808Sep 29, 2026Mozilla
Mitigation bypass in the DOM: Service Workers component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
8.8 High severity
Thunderbird: Improper Privilege Management
CVE-2026-100807Sep 29, 2026Mozilla
Privilege escalation in the DOM: Service Workers component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.
8.1 High severity
Firefox: Origin Validation Error
CVE-2026-100803Sep 29, 2026Mozilla
Same-origin policy bypass in the WebExtensions component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
8.8 High severity
Thunderbird: Improper Privilege Management
CVE-2026-100801Sep 29, 2026Mozilla
Privilege escalation in the DLL Services component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 159, Firefox ESR 153.6, Thunderbird 159, Thunderbird 153.6, Firefox 157, and Firefox ESR 140.
9.6 Critical severity
Firefox: Use After Free
CVE-2026-100800Sep 29, 2026Mozilla
Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.