Critical (9.8). EPSS 3.9% chance of exploitation in the next 30 days.
Memory safety bugs present in Firefox 60, Firefox ESR 60, and Firefox ESR 52.8. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Thunderbird < 60, Thunderbird < 52.9, Firefox ESR < 60.1, Firefox ESR < 52.9, and Firefox < 61.
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
3.9% chance of exploitation in the next 30 days; higher than 90% of CVEs (scores of 2026-10-31)