CVE-2026-27116: Vikunja has Reflected HTML Injection via filter Parameter in its Projects Module

Vikunja is an open-source self-hosted task management platform with 3,300+ GitHub stars. A reflected HTML injection vulnerability exists in the Projects module where the filter URL parameter is rendered into the DOM without output encoding when the user clicks “Filter.” While <script> and <iframe> are blocked, <svg>, <a>, and formatting tags (<h1>, <b>, <u>) render without restriction — enabling SVG-based phishing buttons, external redirect links, and content spoofing within the trusted application origin.

Attack flow: Attacker shares a crafted project filter link (routine Vikunja workflow) → victim opens it → victim clicks “Filter” (standard UI action) → phishing content renders inside trusted Vikunja interface.