The Gecko Media Plugin sandbox allows access to local files that match specific regular expressions. On OS OX, this matching allows access to some data in subdirectories of "/private/var" that could expose personal or temporary data. This has been updated to not allow access to "/private/var" and its subdirectories. Note: this issue only affects OS X. Other operating systems are not affected. This vulnerability affects Firefox < 52 and Thunderbird < 52.
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
1.9% chance of exploitation in the next 30 days; higher than 80% of CVEs (scores of 2026-10-31)