High (8.1) in Mozilla Firefox and Thunderbird. In CISA KEV since 2021-11-03. EPSS 3.0% chance of exploitation in the next 30 days.
Under certain conditions, when running the nsDocShell destructor, a race condition can cause a use-after-free. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Thunderbird < 68.7.0, Firefox < 74.0.1, and Firefox ESR < 68.6.1.
Severity
CVSS 3.1
8.1 high
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
3.0% chance of exploitation in the next 30 days; higher than 87% of CVEs (scores of 2026-10-31)