Mozilla · Firefox · CVE-2019-9809
**Name of the Vulnerable Software and Affected Versions**
Firefox versions prior to 66
**Description**
The issue is related to the management of resources when the source for resources on a page is through an FTP connection. It is possible to trigger a series of modal alert messages for these resources through invalid credentials or locations, leading to a denial of service attack. These messages cannot be immediately dismissed.
**Recommendations**
For versions prior to 66, update to version 66 or later to resolve the issue. As a temporary workaround, consider avoiding the use of FTP connections for resource sourcing until the update is applied. Restrict access to FTP resources to minimize the risk of exploitation.