Critical (9.8). EPSS 3.4% chance of exploitation in the next 30 days.
When manipulating user events in nested loops while opening a document through script, it is possible to trigger a potentially exploitable crash due to poor event handling. This vulnerability affects Firefox < 63, Firefox ESR < 60.3, and Thunderbird < 60.3.
Severity
CVSS 3.0
9.8 critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
3.4% chance of exploitation in the next 30 days; higher than 88% of CVEs (scores of 2026-10-31)