CVE-2026-52781

Description

OpenProject is open-source, web-based project management software. Prior to 17.3.3 and 17.4.1, the HTML sanitizer grants <macro> elements unrestricted data-* attributes via :data wildcard. An attacker injects data-controller=-poll-for-changes- into a work package description, causing Stimulus.js to mount a controller that fetches an attacker-uploaded attachment and passes it to renderStreamMessage(). This executes arbitrary Turbo Stream actions — including redirect_to — in every victim-s authenticated browser session, redirecting them to an attacker-controlled server. This vulnerability is fixed in 17.3.3 and 17.4.1.