CVE-2026-16889
Stored XSS via Pre-Login Notice Image Upload Serves Attacker HTML from Application Origin
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.
INFO
Published Date :
Oct. 29, 2026, 2:16 a.m.
Last Modified :
Oct. 29, 2026, 4:18 a.m.
Remotely Exploit :
Yes !
Source :
9c1820ae-fb77-4810-a8aa-ca46e7474d2f
Affected Products
The following products are affected by CVE-2026-16889
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | MEDIUM | 9c1820ae-fb77-4810-a8aa-ca46e7474d2f | ||||
| CVSS 4.0 | MEDIUM | 9c1820ae-fb77-4810-a8aa-ca46e7474d2f |
Solution
- Update openEQUELLA to version 2026.1 or later.
- Restrict EDIT_SYSTEM_SETTINGS permission.
- Review uploaded pre-login notice images.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-16889.
| URL | Resource |
|---|---|
| https://github.com/openequella/openEQUELLA/security/advisories/GHSA-q2xv-rffq-mj5w | |
| https://openequella.github.io/guides/ |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-16889 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-16889
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-16889 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-16889 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Oct. 29, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-16889', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-10-29T01:51:03.808908Z'} -
New CVE Received by 9c1820ae-fb77-4810-a8aa-ca46e7474d2f
Oct. 29, 2026
Action Type Old Value New Value 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-434 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/16xxx/CVE-2026-16889.json">CVE-2026-16889</a> Added Reference https://github.com/openequella/openEQUELLA/security/advisories/GHSA-q2xv-rffq-mj5w Added Reference https://openequella.github.io/guides/