- Critical 9.6
CVE-2026-100794
Sandbox escape due to incorrect boundary conditions in the Internationalization component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.
Scores
The facts
- Published
- 29 September 2026
- Last changed
- 1 October 2026
- NVD status
- Undergoing Analysis
- Severity
- Critical, CVSS 9.6 out of 10 (version 3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H - Weakness
- Known exploited
- Not in the CISA Known Exploited Vulnerabilities catalogue in this build.
- EPSS
- 0.3% chance of exploitation activity in the next 30 days (percentile 26).
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