Medium (6.5) in mozilla. EPSS 0.7% chance of exploitation in the next 30 days.
Service Workers should not be able to infer information about opaque cross-origin responses; but timing information for cross-origin media combined with Range requests might have allowed them to determine the presence or length of a media file. This vulnerability affects Firefox ESR < 102.5, Thunderbird < 102.5, and Firefox < 107.
Severity
CVSS 3.1
6.5 medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
EPSS
0.7% chance of exploitation in the next 30 days; higher than 54% of CVEs (scores of 2026-10-31)