When adding a range to an object in the DOM, it is possible to use "addRange" to add the range to an incorrect root object. This triggers a use-after-free, resulting in a potentially exploitable crash. This vulnerability affects Firefox < 52 and Thunderbird < 52.
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
1.7% chance of exploitation in the next 30 days; higher than 76% of CVEs (scores of 2026-10-31)