CVE-2026-52781: Opf Openproject

Medium severity, CVSS 6.4. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Opf Openproject: before 17.3.3 (fixed in 17.3.3); from 17.4.0, before 17.4.1 (fixed in 17.4.1)

Published 2026-06-26. Last modified 2026-06-29.