A critical vulnerability has been identified in the Kanboard project management software, assigned CVE-2025-55010 with a CVSS score of 9.1. The flaw allows an authenticated administrator to execute arbitrary code on the server by exploiting an unsafe deserialization process. Successful exploitation could lead to a complete system compromise, enabling an attacker to steal sensitive data, disrupt operations, and pivot to other systems on the network.

The vulnerability is an unsafe deserialization flaw within the ProjectEventActvityFormatter component. An authenticated attacker with administrative privileges can submit a specially crafted serialized payload as part of a project event. The application deserializes this malicious object without proper validation, leading to arbitrary code execution with the permissions of the web server process, resulting in a full compromise of the underlying server.

This vulnerability is rated as critical severity with a CVSS score of 9.1. A successful exploit would grant an attacker complete control over the Kanboard application server. This could lead to the theft of all project data, intellectual property, user credentials, and other sensitive information stored within the system. Furthermore, a compromised server could be used to launch further attacks against the internal network, causing significant operational disruption, financial loss, and severe reputational damage. The requirement for administrator credentials means the risk is highest from an insider threat or a previously compromised administrative account.

Immediate Action: Immediately upgrade all Kanboard instances to version 1.2.47 or later, as recommended by the vendor. After patching, it is crucial to review server and application logs for any signs of compromise that may have occurred prior to the update.

Proactive Monitoring: Organizations should enhance monitoring of Kanboard servers. Look for unusual patterns in application logs, specifically related to project event activity. Monitor for unexpected processes being spawned by the web server (e.g., sh, bash, powershell.exe) and any unauthorized outbound network connections from the server.

Compensating Controls: If immediate patching is not feasible, implement the following controls to mitigate risk:

• Strictly limit and audit all accounts with administrative privileges.
• Deploy a Web Application Firewall (WAF) with rules specifically designed to detect and block deserialization attack patterns.
• Restrict network access to the Kanboard administrative interface to only trusted IP addresses.

Public Exploit Available: False

Given the critical CVSS score of 9.1, it is strongly recommended that organizations prioritize patching this vulnerability immediately. While it is not currently listed on the CISA KEV catalog, its high severity makes it a likely candidate for future inclusion. All instances of Kanboard should be upgraded to version 1.2.47 or newer without delay. If patching must be deferred, the compensating controls listed above should be implemented as a temporary measure, and a plan for patching must be established.