SEC Consult Vulnerability Lab Security Advisory < 20230517-0 >  
title: Stored XSS vulnerability in rename functionality  
product: Wekan (Open-Source kanban)  
vulnerable version: <=6.74  
fixed version: 6.75 or higher  
CVE number: CVE-2023-28485  
impact: Medium  
found: 2022-12-30  
by: Heiner Liesegang (Office Berlin)  
SEC Consult Vulnerability Lab  
An integrated part of SEC Consult.  
SEC Consult is part of Eviden, an Atos business  
Europe | Asia | North America  
Vendor description:  
"WeKan ® is an completely Open Source and Free software collaborative  
kanban board application with MIT license.  
Whether you’re maintaining a personal todo list,  
planning your holidays with some friends,  
or working in a team on your next revolutionary idea, Kanban boards  
are an unbeatable tool to keep your things organized.  
They give you a visual overview of the current state of your project,  
and make you productive by allowing you to focus on the few items that  
matter the most."  
Business recommendation:  
Patch the application with the latest update supplied by the vendor.  
Vulnerability overview/description:  
1) Stored Cross-Site Scripting (CVE-2023-28485)  
An authenticated attacker with the role 'BoardAdmin' is able to rename  
file attachments of Kanban cards. Being an admin of the Wekan instance  
is not required in order for this exploit to work, as any user can  
obtain 'BoardAdmin' privileges by creating a new Kanban board.  
The 'renameAttachment' method does not sanitise user input and allows embedding  
XSS payloads in the specified filename. The stored XSS payload is triggered by  
opening the attachment as the modified filename is displayed in the header bar  
of the file preview.  
Proof of concept:  
1) Stored Cross-Site Scripting (CVE-2023-28485)  
The following steps are necessary to exploit the vulnerability:  
1. Log into the application with at least "user" privileges  
2a. Open a Kanban board in which you have 'BoardAdmin' privileges  
2b. Or, create a new Kanban board otherwise  
3. Create a Kanban card if none exists  
4. Open Kanban card to edit it  
5. If there is no attachment in the card, upload one  
6. Click on "Attachment Actions" under the attachment and select "Rename"  
7. Include arbitrary XSS payload such as the following inside the filename:  
"<script>alert('Stored XSS')</script>"  
8. Select "Save" to embed the XSS payload  
Any user with access to the board clicking on the attachment preview  
triggers the stored XSS. In case the used Kanban board is set to "public"  
any person with a link to the board can access the targeted card and  
trigger the payload inside the attachments' filename.  
Vulnerable / tested versions:  
The following versions have been tested to be vulnerable:  
* v6.64  
* v6.69  
* v6.71  
According to the vendor, all versions before 6.75 are affected as well.  
Vendor contact timeline:  
2023-02-16: Contacting vendor security contact through  
2023-02-21: Vendor responded requesting a recheck of fixes in version 6.75.  
2023-02-27: Security patch is confirmed to fix vulnerability.  
2023-03-14: CVE number requested.  
2023-05-17: Public release of security advisory.  
The vendor provides a patched version which should be installed immediately.  
The version 6.75 or higher provides the corresponding security patch:  
Advisory URL:  
SEC Consult Vulnerability Lab  
SEC Consult is part of Eviden, an Atos business  
Europe | Asia | North America  
About SEC Consult Vulnerability Lab  
The SEC Consult Vulnerability Lab is an integrated part of SEC Consult, part  
of Eviden, an Atos business. It ensures the continued knowledge gain of SEC  
Consult in the field of network and application security to stay ahead of the  
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customers. Hence our customers obtain the most current information about  
vulnerabilities and valid recommendation about the risk profile of new  
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EOF Heiner Liesegang / @2023