Firefox vulnerabilities

870 known vulnerabilities in Firefox from Mozilla. 869 are rated high or critical, and 15 have been exploited in real attacks. Each entry lists the affected versions and the release that fixes it, where the vendor has published one.

870vulnerabilities

253critical

616high

15exploited

8.7average CVSS score

Latest first

7.3 High severity
Firefox: Access of Uninitialized Pointer
CVE-2026-117910Oct 27, 2026Mozilla
Invalid pointer in the JavaScript Engine component. This vulnerability was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Use After Free
CVE-2026-117904Oct 27, 2026Mozilla
Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Use After Free
CVE-2026-117901Oct 27, 2026Mozilla
Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Use After Free
CVE-2026-117900Oct 27, 2026Mozilla
Use-after-free in the DOM: Editor component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Use After Free
CVE-2026-117899Oct 27, 2026Mozilla
Use-after-free in the Networking: HTTP component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
7.3 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-117897Oct 27, 2026Mozilla
Incorrect boundary conditions in the Layout: Tables component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
7.3 High severity
Firefox: Use After Free
CVE-2026-117892Oct 27, 2026Mozilla
Privilege escalation due to use-after-free in the WebRTC: Networking component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
7.3 High severity
Firefox: Use After Free
CVE-2026-117891Oct 27, 2026Mozilla
Use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
7.3 High severity
Firefox: Access of Resource Using Incompatible Type
CVE-2026-117890Oct 27, 2026Mozilla
JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
7.3 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-117889Oct 27, 2026Mozilla
Incorrect boundary conditions in the JavaScript Engine component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Use After Free
CVE-2026-117887Oct 27, 2026Mozilla
Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.1 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-117886Oct 27, 2026Mozilla
Incorrect boundary conditions in the Graphics: Text component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Use After Free
CVE-2026-117884Oct 27, 2026Mozilla
Use-after-free in the Networking component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Use After Free
CVE-2026-117883Oct 27, 2026Mozilla
Use-after-free in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Use After Free
CVE-2026-117881Oct 27, 2026Mozilla
Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
7.3 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-117879Oct 27, 2026Mozilla
Incorrect boundary conditions in the Layout: Tables component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.1 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-117873Oct 27, 2026Mozilla
Incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Use After Free
CVE-2026-117872Oct 27, 2026Mozilla
Use-after-free in the JavaScript: Standard Library component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
7.3 High severity
Firefox: Use After Free
CVE-2026-117870Oct 27, 2026Mozilla
Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Use After Free
CVE-2026-117869Oct 27, 2026Mozilla
Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
9.6 Critical severity
Firefox: Protection Mechanism Failure
CVE-2026-117868Oct 27, 2026Mozilla
Sandbox escape in the DOM: Networking component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
7.3 High severity
Firefox: Use After Free
CVE-2026-117867Oct 27, 2026Mozilla
Use-after-free in the Layout component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
7.3 High severity
Firefox: Use After Free
CVE-2026-117866Oct 27, 2026Mozilla
Privilege escalation due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
9.8 Critical severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-117862Oct 27, 2026Mozilla
Privilege escalation due to incorrect boundary conditions in the Networking component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
9.6 Critical severity
Firefox: Protection Mechanism Failure
CVE-2026-117861Oct 27, 2026Mozilla
Sandbox escape in the DOM: Navigation component. This vulnerability was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.1 High severity
Firefox: Origin Validation Error
CVE-2026-117860Oct 27, 2026Mozilla
Same-origin policy bypass in the DOM: Navigation component. This vulnerability was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
8.8 High severity
Firefox: Improper Privilege Management
CVE-2026-109778Oct 13, 2026Mozilla
Privilege escalation in the WebExtensions 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-2026-109766Oct 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.
8.8 High severity
Firefox: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2026-109762Oct 13, 2026Mozilla
Incorrect boundary conditions in the SVG 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-2026-109760Oct 13, 2026Mozilla
Mitigation bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.1 High severity
Firefox: Origin Validation Error
CVE-2026-109759Oct 13, 2026Mozilla
Site isolation issue in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
8.3 High severity
Firefox: Concurrent Execution using Shared Resource with Improper Synchronization
CVE-2026-109757Oct 13, 2026Mozilla
Sandbox escape due to race condition in the Networking 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-2026-109756Oct 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.