All vulnerabilities
CVE-2026-100794

Thunderbird: Sandbox escape due to incorrect boundary conditions in the Internationalization component

Mozilla Thunderbird
Open in ThreatlineRecord JSON
CVSS
9.6Critical
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.32%Chance of exploitation activity in the next 30 days, higher than 23% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published29 Sep 2026Updated 1 Oct 2026CVE List

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

Description

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.

Text from CVE List

Affected versions 6

  • Thunderbirdunaffected: 140.17 through 140.*CVE List
  • Thunderbirdunaffected: 153.4 through 153.*CVE List
  • Thunderbirdunaffected: 157CVE List
  • Firefoxunaffected: 140.17 through 140.*CVE List
  • Firefoxunaffected: 153.4 through 153.*CVE List
  • Firefoxunaffected: 157CVE List

References 7