published September 30, 2026
MISP contains a stored cross-site script (XSS) vulnerability in the event graph preview feature.
The event graph preview image field was accepted and stored without server-side validation. On the client side, the stored value was rendered into an HTML img element's src attribute via string concatenation, allowing a crafted value to break out of the attribute context and inject arbitrary script.
Preconditions:
- An authenticated MISP user with the ability to create or modify an event graph entry.
- A second user (the victim) who views the event graph and triggers the preview popover.
Impact:
- Execution of arbitrary JavaScript in the victim's browser within the MISP application context.
- Potential theft of session tokens, cookies, or sensitive data accessible to the victim's browser.
- Potential for performing actions on behalf of the victim within the MISP application.
Affected: MISP versions prior to the fix (commit applied after v2.5.48).