Critical (9.8). EPSS 2.6% chance of exploitation in the next 30 days.
A use-after-free vulnerability can occur when an editor DOM node is deleted prematurely during tree traversal while still bound to the document. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.
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
2.6% chance of exploitation in the next 30 days; higher than 85% of CVEs (scores of 2026-10-31)