Shaarli has Stored Cross-Site Scripting (XSS) via Tags Search

Summary

Shaarli is a personal bookmarking service. Versions 0.16.1 and prior contain a stored Cross-Site Scripting (XSS) vulnerability in the tag filtering functionality of Shaarli. An authenticated user can inject arbitrary JavaScript into the tags field when creating a bookmark (Shaare). The malicious payload is stored and later executed when users interact with the "Filter by tag" search feature on the homepage. User-supplied input in the tags field is not properly sanitized or output-escaped before being rendered in the tag filtering interface. When a bookmark is created with a malicious payload inside the tag field, the payload is stored in the database. Later, when a user searches using the "Filter by tag" functionality on the homepage, the application renders matching tags dynamically. If the tag value contains HTML with JavaScript event handlers, it is injected into the DOM. This impacts anyone interacting with the "Filter by tag" search functionality, administrators and privileged users. This issue has been fixed in version 0.16.2.