PYSEC-2022-39

OnionShare is an open source tool that lets you securely and anonymously share files, host websites, and chat with friends using the Tor network. Affected versions of the desktop application were found to be vulnerable to denial of service via an undisclosed vulnerability in the QT image parsing. Roughly 20 bytes lead to 2GB memory consumption and this can be triggered multiple times. To be abused, this vulnerability requires rendering in the history tab, so some user interaction is required. An adversary with knowledge of the Onion service address in public mode or with authentication in private mode can perform a Denial of Service attack, which quickly results in out-of-memory for the server. This requires the desktop application with rendered history, therefore the impact is only elevated. This issue has been patched in version 2.5.