In most scenarios, the attack only worked if the victim viewed both emails and clicked a specific link in the second one.
After researchers disclosed the bug in June 2022, Proton developed and deployed a fix by early July 2022. Proton Exploit
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 vulnerability was strictly limited to the web interface; non-web Proton Mail apps (iOS/Android) were never affected. Protecting Your Data This flaw could have allowed attackers to bypass
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:
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
Ensure you are using the latest version of any Proton applications.