CVE-2026-84126: Vulnerability in Mozilla Firefox
Description
Incorrect boundary conditions in the Layout: Grid component. This vulnerability was fixed in Firefox 155 and Thunderbird 155.
CVSS v3.1
Score 4.3medium
Affected software
Mozilla
Firefox
Mozilla
Thunderbird
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-84126 concerns incorrect boundary conditions in the Layout: Grid component of Mozilla Firefox, which could lead to memory corruption. This vulnerability was identified internally and fixed in Firefox 155. The CVSS v3.1 base score is 4.3, indicating a medium severity with network attack vector, low attack complexity, no privileges required, user interaction required, unchanged scope, and low confidentiality impact. The Mozilla Foundation Security Advisory MFSA 2026-82 confirms the fix in Firefox 155 and classifies the impact as high. There are no known active exploits for this vulnerability.
Potential Impact
The vulnerability could potentially lead to memory corruption due to incorrect boundary conditions in the Layout: Grid component. The impact is classified as high by the vendor advisory, but the CVSS score rates it as medium severity with limited confidentiality impact and no integrity or availability impact. There are no known exploits in the wild, reducing immediate risk.
Mitigation Recommendations
This vulnerability is fixed in Mozilla Firefox version 155. Users and administrators should update to Firefox 155 or later to remediate this issue. No additional mitigation is required as the vendor has provided an official fix.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-09-01T07:25:23.294Z
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-82/","vendor":"Mozilla"}]
Threat ID: 6a96cab0acd9273b49b6854c
Added to database: 09/01/2026, 12:53:04 UTC
Last enriched: 09/07/2026, 14:14:58 UTC
Last updated: 10/14/2026, 18:48:24 UTC
Views: 125
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