GHSA-p23m-cq25-pc4j: Vikunja before 2.7.1 Stored CSS Injection via TipTap Table Cell data-background-color

Vikunja before 2.7.1 contains a stored CSS injection vulnerability that allows authenticated users with project write access to inject arbitrary CSS via unsanitized table-cell data-background-color attributes. Attackers can store crafted task descriptions or comments to render full-viewport phishing overlays or force zero-click outbound background-image requests that deanonymize viewers.