High (8.1) in mozilla. EPSS 0.6% chance of exploitation in the next 30 days.
It was possible for a web extension with minimal permissions to create a `StreamFilter` which could be used to read and modify the response body of requests on any site. This vulnerability affects Firefox < 129, Firefox ESR < 115.14, Firefox ESR < 128.1, Thunderbird < 128.1, and Thunderbird < 115.14.
Severity
CVSS 3.1
8.1 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
EPSS
0.6% chance of exploitation in the next 30 days; higher than 48% of CVEs (scores of 2026-10-31)