CVE-2026-100819: Vulnerability in Mozilla Firefox
Sandbox escape due to incorrect boundary conditions in the XPCOM component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
AI Analysis
Technical Summary
This vulnerability in Mozilla Firefox is due to incorrect boundary conditions in the XPCOM component, which leads to a sandbox escape. A sandbox escape vulnerability allows malicious code that is confined within a restricted environment to break out and execute with higher privileges or access unauthorized resources. Mozilla has addressed this issue by releasing fixes in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. The vendor advisory lists this vulnerability among multiple high-impact security issues fixed in these releases.
Potential Impact
Successful exploitation of this vulnerability could allow an attacker to escape the sandbox environment in Firefox, potentially leading to execution of arbitrary code with elevated privileges or access to restricted system resources. This elevates the risk of further compromise on affected systems. However, there are no reports of active exploitation in the wild.
Mitigation Recommendations
Mozilla has released official fixes for this vulnerability in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. Users and administrators should update affected Firefox installations to these versions or later to remediate the issue. No additional mitigation steps are required beyond applying the official patches.
CVE-2026-100819: Vulnerability in Mozilla Firefox
Description
Sandbox escape due to incorrect boundary conditions in the XPCOM component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, 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 in Mozilla Firefox is due to incorrect boundary conditions in the XPCOM component, which leads to a sandbox escape. A sandbox escape vulnerability allows malicious code that is confined within a restricted environment to break out and execute with higher privileges or access unauthorized resources. Mozilla has addressed this issue by releasing fixes in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. The vendor advisory lists this vulnerability among multiple high-impact security issues fixed in these releases.
Potential Impact
Successful exploitation of this vulnerability could allow an attacker to escape the sandbox environment in Firefox, potentially leading to execution of arbitrary code with elevated privileges or access to restricted system resources. This elevates the risk of further compromise on affected systems. However, there are no reports of active exploitation in the wild.
Mitigation Recommendations
Mozilla has released official fixes for this vulnerability in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. Users and administrators should update affected Firefox installations 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
- 2026-09-26T19:18:30.736Z
- 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/mfsa2026-98/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-99/","vendor":"Mozilla"}]
Threat ID: 6abbb3f7f7a7c541066409bf
Added to database: 09/29/2026, 12:49:59 UTC
Last enriched: 09/29/2026, 13:03:29 UTC
Last updated: 09/29/2026, 15:30:19 UTC
Views: 4
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