MISP contains a stored cross‑site scripting (XSS) vulnerability in the Overmind theme's statistics views. The event General card and the server/feed preview card constructed donut chart legend labels by directly concatenating object name or category keys into an innerHTML string without HTML‑encoding. Because MISP object names are user‑controllable by any authenticated user with sufficient permissions to create or modify such objects, an attacker could craft a name containing malicious markup. When any other user viewed the affected Overmind dashboard, the injected markup would be interpreted as live HTML/JavaScript in the victim's browser, executing in the context of the MISP application origin. This could allow session hijacking, data exfiltration, or arbitrary actions performed on behalf of the victim. The vulnerability requires the attacker to have low‑level authenticated access to create or rename an object whose name is rendered in the legend, and the victim to view the Overmind event or server preview page. No special browser conditions or race conditions are required.

The flaw exists in the MISP platform (misp:misp) when the Overmind theme is used. All versions that have the vulnerable legend rendering code are affected; the fix was applied in the Git commit referenced. No specific version range is listed, so any installation presenting the Overmind dashboard and allowing object name manipulation without output encoding is at risk.

The CVSS score of 8.5 indicates a high impact, but the presence of a stored XSS vector makes exploitation straightforward for an authenticated attacker. The EPSS score is below 1 %, indicating that, while technically easy to exploit, the likelihood of active exploitation at this time is low. The vulnerability is not in the CISA KEV list. Attackers would need to craft an object name and have users browse the affected pages; no special setup beyond normal authenticated interactions is required.