CVE-2017-7765: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 1.4% chance of exploitation in the next 30 days.

The "Mark of the Web" was not correctly saved on Windows when files with very long names were downloaded from the Internet. Without the Mark of the Web data, the security warning that Windows displays before running executables downloaded from the Internet is not shown. Note: This attack only affects Windows operating systems. Other operating systems are unaffected. This vulnerability affects Firefox < 54, Firefox ESR < 52.2, and Thunderbird < 52.2.

Affected products

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

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