High (7.5). EPSS 1.6% chance of exploitation in the next 30 days.
A legacy extension's non-contentaccessible, defined resources can be loaded by an arbitrary web page through script. This script does this by using a maliciously crafted path string to reference the resources. Note: this vulnerability does not affect WebExtensions. This vulnerability affects Firefox < 59.
Severity
CVSS 3.0
7.5 high
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
1.6% chance of exploitation in the next 30 days; higher than 76% of CVEs (scores of 2026-10-31)