MISP contains a stored cross-site scripting (XSS) vulnerability in the index table rendering of the remote event preview. The count field template escaped the associated link URL but rendered the field value without HTML encoding. An attacker with the ability to create or modify events on a linked (remote) MISP server could craft an event identifier containing HTML or JavaScript markup. When a user on the local MISP instance views the remote event preview index, the unescaped value is rendered directly in the browser, allowing arbitrary script execution in the victim's session.
Preconditions:
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A linked/remote MISP server is configured and connected to the local instance.
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The attacker has sufficient access on the linked server to create or modify an event with a crafted identifier.
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A victim user on the local instance views the remote event preview index page.
Impact:
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Execution of arbitrary JavaScript in the context of the MISP web application.
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Potential session hijacking, data exfiltration, or unauthorized actions performed on behalf of the authenticated user.
Affected versions: <2.5.48.
The vulnerability is remediated by applying HTML entity encoding to the count field value before it is rendered in the view template. This ensures that any HTML or script markup contained in the value from a remote server is neutralized and displayed as inert text rather than being interpreted by the browser.