CVE-2026-16889

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

State: Published
Severity: 4.8 Medium
Published: Oct 29, 2026
Updated: Oct 29, 2026
Reserved: Jul 24, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	4.8 Medium	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	MON-CSIRT

Weaknesses

CWE-434 Unrestricted upload of file with dangerous type

Affected Products

Product	Versions
openEQUELLAApereo Foundation	2019.1 to before 2026.1Affected

References

https://github.com/openequella/openEQUELLA/security/advisories/GHSA-q2xv-rffq-mj5wvendor-advisory
https://openequella.github.io/guides/product

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