Vulnerabilities
PortSwigger's CSS Attacks Break Webmail Defenses in Outlook, Gmail, Proton, and More
New research from PortSwigger's Gareth Heyes shows CSS inside an email can slip past its message boundary and interfere with the webmail interface across Outlook, Gmail, Fastmail, Proton Mail, Yahoo Mail, and AOL Mail — stealing passwords and tokens or hijacking trusted UI actions.