High (8.8) in mozilla. EPSS 18% chance of exploitation in the next 30 days.
An attacker could have sent a message to the parent process where the contents were used to double-index into a JavaScript object, leading to prototype pollution and ultimately attacker-controlled JavaScript executing in the privileged parent process. This vulnerability affects Firefox ESR < 91.9.1, Firefox < 100.0.2, Firefox for Android < 100.3.0, and Thunderbird < 91.9.1.
Severity
CVSS 3.1
8.8 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS
18% chance of exploitation in the next 30 days; higher than 97% of CVEs (scores of 2026-10-31)