CVE-2026-84143
Received Received - Intake

Memory Corruption Vulnerability in Firefox

Publication date: 2026-09-01

Last updated on: 2026-09-01

Assigner: Mozilla Corporation

Description
Internally found bugs present in Firefox 154, Firefox ESR 153.1 and Firefox ESR 140.14. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, and Firefox ESR 153.2.

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Meta Information

Published
2026-09-01
Last Modified
2026-09-01
Generated
2026-09-01
AI Q&A
2026-09-01
EPSS Evaluated
N/A
NVD
CVE-2026-84143
EUVD
EUVD-2026-69091

Affected Vendors & Products

Showing 6 associated CPEs
Vendor Product Version / Range
mozilla firefox 154
mozilla firefox 153.1
mozilla firefox 140.14
mozilla firefox 155
mozilla firefox 140.15
mozilla firefox 153.2

Helpful Resources

Exploitability

CWE
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability involves multiple internally found bugs in Firefox versions 154, ESR 153.1, and ESR 140.14. Some of these bugs could lead to memory corruption or other security issues, potentially allowing exploitation with sufficient effort. The issue was addressed in later versions: Firefox 155, ESR 140.15, and ESR 153.2.

Detection Guidance

Detection requires checking Firefox version against vulnerable releases. Use commands like 'firefox --version' or check installed package versions via system package managers (e.g., 'apt list --installed | grep firefox' on Debian/Ubuntu). Compare versions to Firefox 154, ESR 153.1, or ESR 140.14.

Impact Analysis

If exploited, this vulnerability could allow attackers to execute arbitrary code, gain unauthorized access, or cause system crashes. Users running affected Firefox versions may be at risk of data breaches or malware infections.

Mitigation Strategies

Upgrade Firefox to version 155 or later, Firefox ESR 140.15 or later, or Firefox ESR 153.2 or later. Disable automatic updates temporarily if needed, but prioritize patching to address potential memory corruption risks.

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