CVE-2026-16889

Stored XSS via Pre-Login Notice Image Upload Serves Attacker HTML from Application Origin

Published Oct 29, 2026 CVSS 4.0 · 4.8 Medium EPSS < 1% KEV · Not listed
Description
In openEQUELLA before 2026.1, the pre-login notice image upload endpoint (PUT /api/preloginnotice/image/{name}) does not validate the type of uploaded files and serves them with a Content-Type derived from the supplied filename. A user holding the EDIT_SYSTEM_SETTINGS permission can upload an HTML file that is then served as text/html from the openEQUELLA origin, resulting in stored cross-site scripting. Unauthenticated exploitation is possible where EDIT_SYSTEM_SETTINGS has been granted to the guest user or everyone.

Remediation

Vendor Solution

Update to vendor recommended versions

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Apereo Foundation
Apereo Foundation openequella
Vendors & Products Apereo Foundation
Apereo Foundation openequella
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description In openEQUELLA before 2026.1, the pre-login notice image upload endpoint (PUT /api/preloginnotice/image/{name}) does not validate the type of uploaded files and serves them with a Content-Type derived from the supplied filename. A user holding the EDIT_SYSTEM_SETTINGS permission can upload an HTML file that is then served as text/html from the openEQUELLA origin, resulting in stored cross-site scripting. Unauthenticated exploitation is possible where EDIT_SYSTEM_SETTINGS has been granted to the guest user or everyone.
Title Stored XSS via Pre-Login Notice Image Upload Serves Attacker HTML from Application Origin
Weaknesses CWE-434
References
Metrics cvssV4_0

{'score': 4.8, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
MON-CSIRT
Published
Updated
Oct 29, 2026, 2:02 AM
Reserved
Jul 24, 2026, 5:06 AM
Status
Deferred
Published
Oct 29, 2026, 2:16 AM
Modified
Oct 29, 2026, 3:56 PM