Proton Exploit Info

The attack required a specific sequence of actions to succeed, which limited its real-world viability:

Shift the tone (e.g., for developers or simpler for general users). Proton Exploit

This incident serves as a reminder that no system is 100% secure, but active collaboration with the security community—often incentivized by Proton's Bug Bounty Program —is essential for maintaining privacy. To stay secure, users should: The attack required a specific sequence of actions

If successful, the script would run in the victim's session, allowing the attacker to "see" what the user sees—effectively stealing the decrypted content of their inbox. Proton's Response and Resolution Proton's Response and Resolution In June 2022, security

In June 2022, security researchers from SonarSource discovered a critical Cross-Site Scripting (XSS) vulnerability in the open-source code of Proton Mail. This flaw could have allowed attackers to bypass end-to-end encryption to steal decrypted emails and impersonate victims. The Discovery

In most scenarios, the attack only worked if the victim viewed both emails and clicked a specific link in the second one.

The Sonar Research team identified the vulnerability during a routine audit of Proton's open-source repositories. The issue stemmed from how the web application handled user-controlled HTML. While senders need the ability to style messages, failing to properly sanitize certain tags can allow malicious tags to execute in a reader's browser. How the Exploit Worked