An error in argument length checking in JavaScript, leading to potential integer overflows or other bounds checking issues. This vulnerability affects Thunderbird < 45.5, Firefox ESR < 45.5, and Firefox < 50.
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
3.5% chance of exploitation in the next 30 days; higher than 89% of CVEs (scores of 2026-10-31)