CVE-2026-109721
Received Received - Intake

Incorrect Boundary Conditions in Firefox JavaScript Engine JIT

Publication date: 2026-10-13

Last updated on: 2026-10-13

Assigner: Mozilla Corporation

Description
Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

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Meta Information

Published
2026-10-13
Last Modified
2026-10-13
Generated
2026-10-19
AI Q&A
2026-10-13
EPSS Evaluated
2026-10-18
NVD
CVE-2026-109721
EUVD
EUVD-2026-98492

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
mozilla firefox to 158 (inc)
mozilla firefox_esr to 153.5 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability involves incorrect boundary conditions in the JavaScript Engine's JIT component. It was addressed in Firefox 158 and Firefox ESR 153.5.

Detection Guidance

Detection requires checking Firefox version. If using Firefox, run: about:support in the address bar to check version. If version is below 158 or Firefox ESR below 153.5, the system is vulnerable. No specific commands detect exploitation directly.

Impact Analysis

An attacker could exploit this flaw to execute arbitrary code or cause a denial of service by triggering incorrect memory handling in the JavaScript Engine.

Compliance Impact

The provided CVE data does not specify how this vulnerability impacts compliance with standards like GDPR or HIPAA. The description focuses solely on the technical nature of the flaw in Firefox's JavaScript Engine JIT component.

Mitigation Strategies

Update Firefox to version 158 or later and Firefox ESR to version 153.5 or later to address the vulnerability.

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