CVE-2017-7761: Mozilla Firefox

Medium severity, CVSS 5.5. EPSS: 0.3% chance of exploitation in the next 30 days.

The Mozilla Maintenance Service "helper.exe" application creates a temporary directory writable by non-privileged users. When this is combined with creation of a junction (a form of symbolic link), protected files in the target directory of the junction can be deleted by the Mozilla Maintenance Service, which has privileged access. Note: This attack requires local system access and only affects Windows. Other operating systems are not affected. This vulnerability affects Firefox ESR < 52.2 and Firefox < 54.

Affected products

• Mozilla Firefox: before 52.2.0 (fixed in 52.2.0); before 54.0 (fixed in 54.0)

Published 2018-06-11. Last modified 2026-06-17.