Executive Summary

[{'type': 'paragraph', 'content': "CVE-2026-24885 is a Cross-Site Request Forgery (CSRF) vulnerability in the Kanboard project management software, specifically in the ProjectPermissionController's changeUserRole action."}, {'type': 'paragraph', 'content': 'The vulnerability exists because the server does not strictly enforce the application/json Content-Type header for requests that modify user roles. Instead, it also accepts requests with the text/plain Content-Type, which allows attackers to craft malicious forms that bypass typical CSRF protections.'}, {'type': 'paragraph', 'content': 'An attacker can exploit this by tricking an authenticated admin into visiting a malicious webpage containing a specially crafted form that submits a POST request with text/plain encoding to change project user roles without the admin’s consent.'}, {'type': 'paragraph', 'content': 'This results in unauthorized modification of project user roles, effectively allowing privilege escalation within the application.'}] [1]

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Impact Analysis

This vulnerability allows an attacker to escalate privileges within the Kanboard application by modifying project user roles without authorization.

Specifically, if an authenticated admin visits a malicious site, the attacker can change user roles from lower privileges (e.g., project-viewer) to higher privileges (e.g., project-manager).

The impact affects the integrity of the application by enabling unauthorized role changes, but it does not affect confidentiality or availability.

The attack requires low complexity and some user interaction (the admin visiting a malicious webpage), and it is network-based.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by monitoring for POST requests to the changeUserRole endpoint that use the Content-Type header set to text/plain instead of application/json. Such requests indicate attempts to exploit the CSRF vulnerability by submitting unauthorized role changes.'}, {'type': 'paragraph', 'content': 'You can use network traffic inspection tools like tcpdump or Wireshark to filter HTTP POST requests with the text/plain Content-Type targeting the Kanboard application.'}, {'type': 'list_item', 'content': "Example tcpdump command to capture such requests: tcpdump -i any -A -s 0 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep -i 'POST /changeUserRole' -A 10"}, {'type': 'list_item', 'content': 'Use curl or similar tools to test if the server accepts text/plain Content-Type for role changes by sending a crafted POST request with text/plain header to the changeUserRole endpoint.'}, {'type': 'paragraph', 'content': 'Additionally, reviewing server logs for POST requests to the changeUserRole endpoint with Content-Type other than application/json can help detect exploitation attempts.'}] [1]

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Mitigation Strategies

The immediate and most effective mitigation is to upgrade Kanboard to version 1.2.50 or later, where this vulnerability is fixed.

The fix includes enforcing strict CSRF protection on project role modification endpoints and requiring that requests use the application/json Content-Type header.

• Apply the official patch or update that adds CSRF token validation to the changeUserRole and changeGroupRole actions.
• Ensure that the server rejects any requests to role modification endpoints that are not AJAX requests or do not have the correct JSON content type.

Until the update is applied, restrict access to the Kanboard application to trusted networks and educate administrators to avoid visiting untrusted or suspicious websites while authenticated.

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