CVE-2020-15654

Name of the Vulnerable Software and Affected Versions Firefox ESR versions prior to 78.1 Firefox versions prior to 79 Thunderbird versions prior to 78.1

Description A custom cursor using CSS could make it look like the user is interacting with the user interface when they are not, leading to a perceived broken state. This issue could be exploited by tech support scammers to create an "evil cursor" attack, keeping victims from easily navigating away from fake virus warning pages. The problem lies in the browser's legitimate permission for modifying the standard cursor, which can be abused by replacing the cursor with an image identical to the standard one, making it difficult for users to click on certain buttons.

Recommendations For Firefox ESR versions prior to 78.1, update to version 78.1 or later. For Firefox versions prior to 79, update to version 79 or later. For Thunderbird versions prior to 78.1, update to version 78.1 or later. As a temporary workaround, consider using the keyboard shortcut Alt+F4 to close the browser window.