High (7.5). EPSS 2.5% chance of exploitation in the next 30 days.
A possibly exploitable crash triggered during layout and manipulation of bidirectional unicode text in concert with CSS animations. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 52.1, and Firefox < 53.
Severity
CVSS 3.0
7.5 high
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
2.5% chance of exploitation in the next 30 days; higher than 84% of CVEs (scores of 2026-10-31)