CVE-2019-9807: Mozilla Firefox

Medium severity, CVSS 4.3. EPSS: 0.8% chance of exploitation in the next 30 days.

When arbitrary text is sent over an FTP connection and a page reload is initiated, it is possible to create a modal alert message with this text as the content. This could potentially be used for social engineering attacks. This vulnerability affects Firefox < 66.

Affected products

• Mozilla Firefox: before 66.0 (fixed in 66.0)

Published 2019-04-26. Last modified 2026-06-17.