CVE-2026-52823 in Kimai
Summary
by MITRE • 09/15/2026
Kimai is an open-source time tracking application. Prior to 2.58.0, TimesheetController exposes GET /api/timesheets/{id}/stop and GET /api/timesheets/{id}/restart, which reuse an authenticated browser session and perform state-changing operations through GET requests without a request-forgery defense. A remote attacker can cause a logged-in user to request either route from attacker-controlled content, stopping a running timesheet or restarting a historical entry to create and start a new timesheet without the user's consent. The unauthorized changes can corrupt time records, billing, reports, approvals, and audits. This issue is fixed in version 2.58.0.
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Analysis
by VulDB Data Team • 09/15/2026
Kimai is an open-source application designed for professional time tracking, widely used by individuals and organizations to monitor work hours, manage projects, and generate accurate billing records. The security flaw identified affects versions prior to 2.58.0 and centers on the improper implementation of state-changing operations within its RESTful API endpoints. Specifically, the TimesheetController exposes two critical routes: GET /api/timesheets/{id}/stop and GET /api/timesheets/{id}/restart. These endpoints are designed to modify application state by either halting an active timesheet or restarting a historical entry to initiate a new one. However, these operations rely exclusively on HTTP GET requests, which fundamentally violates the principle that actions causing side effects should not be performed via safe methods intended for data retrieval only.
The core technical vulnerability lies in the absence of Cross-Site Request Forgery defenses for these specific endpoints. Because the application reuses authenticated browser sessions and does not implement anti-CSRF tokens or other request-forgery mitigations, an attacker can craft malicious web content that automatically triggers these GET requests when accessed by a logged-in user. This is a classic implementation error where the server fails to distinguish between legitimate user-initiated actions and automated requests generated by third-party sites. The vulnerability maps directly to CWE-352, which describes Cross-Site Request Forgery (CSRF), as well as CWE-601, URL Redirection to Untrusted Site, if the attacker leverages redirection techniques to mask the malicious intent. Furthermore, from a threat modeling perspective, this behavior aligns with ATT&CK technique T1534, which covers Internal Spearphishing or Social Engineering leading to unauthorized actions within an application environment.
The operational impact of this vulnerability is significant and multifaceted. A remote attacker can force a victim who has an active Kimai session to stop their current timesheet without consent, potentially disrupting work tracking for critical projects. More severely, the ability to restart historical entries allows an attacker to create new timesheets based on past data. This capability enables malicious actors to manipulate time records, leading to inaccurate billing calculations and distorted project reports. In professional environments where time sheets are tied directly to payroll or client invoicing, such unauthorized modifications can result in financial loss for both the employee and the organization. Additionally, these actions compromise the integrity of audit trails and approval workflows, as the system will record changes that were not genuinely authorized by the user, undermining trust in the application's data reliability.
To mitigate this vulnerability, organizations must upgrade to Kimai version 2.58.0 or later, where the developers have addressed the issue by implementing appropriate safeguards against request forgery for state-changing operations. In environments where immediate patching is not feasible, temporary mitigations should include enforcing strict Content Security Policy headers that restrict cross-origin requests and ensuring that all API endpoints requiring state changes utilize HTTP POST methods with CSRF token validation rather than GET requests. Additionally, administrators should review session management policies to ensure that authentication tokens are short-lived and securely managed to reduce the window of opportunity for such attacks. Regular security audits focusing on RESTful API design principles can help prevent similar misconfigurations in future updates or custom integrations.