High (8.8). EPSS 3.1% chance of exploitation in the next 30 days.
A use-after-free vulnerability can occur when script uses mutation events to move DOM nodes between documents, resulting in the old document that held the node being freed but the node still having a pointer referencing it. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 60, Thunderbird < 52.9, Firefox ESR < 60.1, Firefox ESR < 52.9, and Firefox < 61.
Severity
CVSS 3.0
8.8 high
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS
3.1% chance of exploitation in the next 30 days; higher than 87% of CVEs (scores of 2026-10-31)