CVE-2026-100776: Vulnerability in Mozilla Firefox
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17.
AI Analysis
Technical Summary
This vulnerability involves a use-after-free condition in the JavaScript WebAssembly component of Mozilla Firefox. Use-after-free vulnerabilities occur when a program continues to use memory after it has been freed, potentially leading to memory corruption or arbitrary code execution. Mozilla fixed this issue in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17 as part of a security update announced on September 29, 2026. The advisory lists this vulnerability among several others fixed in the same release cycle, all rated with high impact.
Potential Impact
The vulnerability has a high impact rating according to Mozilla, indicating it could allow an attacker to cause memory corruption or potentially execute arbitrary code via the WebAssembly component. However, there are no reports of active exploitation in the wild.
Mitigation Recommendations
Users and administrators should update affected Firefox installations to Firefox ESR 153.4, Firefox 157, or Firefox ESR 140.17 or later to remediate this vulnerability. Applying the official Mozilla security update fully addresses this issue.
CVE-2026-100776: Vulnerability in Mozilla Firefox
Description
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17.
CVSS v3.1
Score 8.8high
Affected software
Mozilla
Firefox
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves a use-after-free condition in the JavaScript WebAssembly component of Mozilla Firefox. Use-after-free vulnerabilities occur when a program continues to use memory after it has been freed, potentially leading to memory corruption or arbitrary code execution. Mozilla fixed this issue in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17 as part of a security update announced on September 29, 2026. The advisory lists this vulnerability among several others fixed in the same release cycle, all rated with high impact.
Potential Impact
The vulnerability has a high impact rating according to Mozilla, indicating it could allow an attacker to cause memory corruption or potentially execute arbitrary code via the WebAssembly component. However, there are no reports of active exploitation in the wild.
Mitigation Recommendations
Users and administrators should update affected Firefox installations to Firefox ESR 153.4, Firefox 157, or Firefox ESR 140.17 or later to remediate this vulnerability. Applying the official Mozilla security update fully addresses this issue.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-09-26T19:15:31.965Z
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-100/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-97/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-99/","vendor":"Mozilla"}]
Threat ID: 6abbb3eff7a7c54106640979
Added to database: 09/29/2026, 12:49:51 UTC
Last enriched: 09/29/2026, 13:32:59 UTC
Last updated: 09/29/2026, 18:20:12 UTC
Views: 2
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