In openEQUELLA before 2026.2, the pre-login notice is stored as HTML and rendered on the legacy logon page without encoding or sanitisation. A user holding the EDIT_SYSTEM_SETTINGS permission can set a notice containing an arbitrary script (PUT /api/preloginnotice), resulting in stored cross-site scripting on the login page. Unauthenticated exploitation is possible where EDIT_SYSTEM_SETTINGS has been granted to the guest user or Everyone
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