CVE-2026-100818: Vulnerability in Mozilla Firefox
Sandbox escape due to use-after-free in the Widget: Gtk component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17.
AI Analysis
Technical Summary
This vulnerability is a use-after-free in the Widget: Gtk component of Mozilla Firefox that leads to sandbox escape. A use-after-free occurs when a program continues to use memory after it has been freed, which can cause undefined behavior including execution of arbitrary code. The sandbox escape means that an attacker could potentially bypass the browser's security sandbox, increasing the risk of system compromise. Mozilla fixed this issue in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17.
Potential Impact
Successful exploitation of this vulnerability could allow an attacker to escape the Firefox sandbox, potentially leading to execution of arbitrary code outside the browser's restricted environment. This elevates the risk of system compromise beyond the browser context.
Mitigation Recommendations
Mozilla has released official fixes for this vulnerability in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17. Users and administrators should update to these versions or later to remediate the issue. No additional mitigation steps are required beyond applying the official patches.
CVE-2026-100818: Vulnerability in Mozilla Firefox
Description
Sandbox escape due to use-after-free in the Widget: Gtk component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17.
CVSS v3.1
Score 9.6critical
Affected software
Mozilla
Firefox
pkg:github/mozilla/firefoxRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability is a use-after-free in the Widget: Gtk component of Mozilla Firefox that leads to sandbox escape. A use-after-free occurs when a program continues to use memory after it has been freed, which can cause undefined behavior including execution of arbitrary code. The sandbox escape means that an attacker could potentially bypass the browser's security sandbox, increasing the risk of system compromise. Mozilla fixed this issue in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17.
Potential Impact
Successful exploitation of this vulnerability could allow an attacker to escape the Firefox sandbox, potentially leading to execution of arbitrary code outside the browser's restricted environment. This elevates the risk of system compromise beyond the browser context.
Mitigation Recommendations
Mozilla has released official fixes for this vulnerability in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17. Users and administrators should update to these versions or later to remediate the issue. No additional mitigation steps are required beyond applying the official patches.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-09-26T19:18:28.415Z
- 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: 6abbb3f7f7a7c541066409be
Added to database: 09/29/2026, 12:49:59 UTC
Last enriched: 09/29/2026, 13:03:32 UTC
Last updated: 09/29/2026, 13:53:58 UTC
Views: 4
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