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Mozilla Firefox ESR22 vulnerabilities

Risk 33
Severity
7

Security Vulnerabilities fixed in Firefox ESR 140.17

First published (updated )
Advisory
MFSA2026-99

Site isolation issue in the Panning and Zooming component

Risk 24
Severity
4.7
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

Site isolation issue in the Panning and Zooming 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.

First published (updated )
CVE-2026-100821

Use-after-free in the Graphics: Canvas2D component

Risk 77
Severity
8.8
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Use-after-free in the Graphics: Canvas2D 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.

First published (updated )
CVE-2026-100789

Undefined behavior in the DOM: Streams component

Risk 59
Severity
8.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Undefined behavior in the DOM: Streams 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.

First published (updated )
CVE-2026-100771

Use-after-free in the JavaScript: WebAssembly component

Risk 77
Severity
8.8
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Use-after-free in the JavaScript: WebAssembly 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.

First published (updated )
CVE-2026-100769

Uninitialized memory in the Storage: Quota Manager component

Risk 59
Severity
8.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Uninitialized memory in the Storage: Quota Manager 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.

First published (updated )
CVE-2026-100759

Privilege escalation in the DOM: Service Workers component

Risk 77
Severity
8.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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.

First published (updated )
CVE-2026-100807

JIT miscompilation in the JavaScript: WebAssembly component

Risk 47
Severity
7.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

JIT miscompilation in the JavaScript: WebAssembly 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.

First published (updated )
CVE-2026-100792

Use-after-free in the Layout: Text and Fonts component

Risk 77
Severity
8.8
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Use-after-free in the Layout: Text and Fonts 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.

First published (updated )
CVE-2026-100784

Use-after-free in the Graphics: Canvas2D component

Risk 77
Severity
8.8
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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.

First published (updated )
CVE-2026-100832

Uninitialized memory in the Audio/Video component

Risk 22
Severity
4.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

Uninitialized memory in the Audio/Video 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.

First published (updated )
CVE-2026-100783

Sandbox escape due to use-after-free in the DOM: Content Processes component

Risk 80
Severity
9.6
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Sandbox escape due to use-after-free in the DOM: Content Processes 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.

First published (updated )
CVE-2026-100762

Information disclosure in the Networking: JAR component

Risk 22
Severity
4.3
Infoleak
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Information disclosure in the Networking: JAR 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.

First published (updated )
CVE-2026-100766

Use-after-free in the XSLT component

Risk 77
Severity
8.8
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Use-after-free in the XSLT 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.

First published (updated )
CVE-2026-100790

Use-after-free in the Widget component

Risk 77
Severity
8.8
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Use-after-free in the Widget 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.

First published (updated )
CVE-2026-100757

Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component

Risk 80
Severity
9.6
Buffer Overflow
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender 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.

First published (updated )
CVE-2026-100781

Privilege escalation in the Address Bar component

Risk 77
Severity
8.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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.

First published (updated )
CVE-2026-100820

Sandbox escape due to use-after-free in the DOM: Content Processes component

Risk 80
Severity
9.6
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Sandbox escape due to use-after-free in the DOM: Content Processes 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.

First published (updated )
CVE-2026-100770

Sandbox escape due to use-after-free in the Graphics component

Risk 80
Severity
9.6
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Sandbox escape due to use-after-free in the Graphics 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.

First published (updated )
CVE-2026-100786

Use-after-free in the DOM: Core & HTML component

Risk 77
Severity
8.8
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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, Firefox ESR 115.42, and Firefox ESR 140.17.

First published (updated )
CVE-2026-100791

Use-after-free in the DOM: Core & HTML component

Risk 77
Severity
8.8
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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, Firefox ESR 115.42, and Firefox ESR 140.17.

First published (updated )
CVE-2026-100774

Same-origin policy bypass in the WebExtensions component

Risk 59
Severity
8.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

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.

First published (updated )
CVE-2026-100803

Use-after-free in the JavaScript: WebAssembly component

Risk 77
Severity
8.8
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Use-after-free in the JavaScript: WebAssembly 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.

First published (updated )
CVE-2026-100776

Mozilla FirefoxSpoofing issue in the Networking: HTTP component

Risk 34
Severity
5.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L

Spoofing issue in the Networking: HTTP component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.

First published (updated )
CVE-2026-100822

Mozilla FirefoxSame-origin policy bypass in the DevTools component

Risk 59
Severity
8.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

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.

First published (updated )
CVE-2026-100809

Mozilla FirefoxDenial-of-service in the Storage: StorageManager component

Risk 37
Severity
6.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Denial-of-service in the Storage: StorageManager component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.

First published (updated )
CVE-2026-100826

Mozilla FirefoxUse-after-free in the DOM: UI Events & Focus Handling component

Risk 77
Severity
8.8
Use After Free
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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.

First published (updated )
CVE-2026-100831

Mozilla FirefoxPrivilege escalation in the Places component

Risk 77
Severity
8.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Privilege escalation in the Places component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.

First published (updated )
CVE-2026-100824

Mozilla FirefoxSandbox escape in the Security: Process Sandboxing component

Risk 80
Severity
9.6
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.

First published (updated )
CVE-2026-100760

Mozilla FirefoxUninitialized memory in the Graphics: WebGPU component

Risk 22
Severity
4.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

Uninitialized memory in the Graphics: WebGPU component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.

First published (updated )
CVE-2026-100806

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