CVE-2026-84805 in Kimai
Summary
by MITRE • 09/02/2026
Kimai versions from 2.61.0 before 2.63.0 fail to disable admin-only work-contract preferences for low-privilege users in the PATCH /api/users/{id}/preferences endpoint. Although the web interface gates these employment-contract fields behind the contract_other_profile admin permission, the WorkContractPreferenceSubscriber (introduced in 2.61.0) registers the preferences as enabled without a permission check, so an authenticated regular user can use the API to modify their own admin-only work-contract data. The issue is fixed in 2.63.0 by applying the same permission check to the API endpoint.
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Analysis
by VulDB Data Team • 09/02/2026
The vulnerability identified in Kimai versions ranging from 2.61.0 up to, but not including, version 2.63.0 represents a critical failure in access control mechanisms within the application's RESTful API layer. This flaw specifically affects the PATCH /api/users/{id}/preferences endpoint, which is designed to allow users to update their profile settings and preferences. While the web-based user interface correctly enforces security policies by restricting certain employment-contract fields behind the contract_other_profile administrative permission, this protection does not extend to the API endpoints. The root cause lies in the WorkContractPreferenceSubscriber component, introduced in version 2.61.0, which registers these specific preferences as enabled without performing any corresponding authorization checks. This architectural inconsistency creates a significant security gap where the backend logic fails to validate whether the requesting user possesses the necessary privileges to modify sensitive administrative data.
From a technical perspective, this issue is classified under CWE-862, Missing Authorization Check, and aligns with MITRE ATT&CK technique T1078, Valid Accounts, as it allows an authenticated attacker to escalate their effective permissions by manipulating backend state through the API. An authenticated regular user can exploit this flaw by sending a crafted HTTP PATCH request to the specified endpoint, including fields related to work contracts that are intended for administrative use only. Because the WorkContractPreferenceSubscriber processes these requests without verifying the user's role or permission set against the contract_other_profile requirement, the system accepts and applies changes that should have been rejected. This bypass of server-side validation demonstrates a classic case where frontend security controls are mistakenly assumed to be sufficient, ignoring the necessity for robust backend enforcement in all interaction vectors including API calls.
The operational impact of this vulnerability is substantial, as it allows low-privilege users to alter administrative configuration data that could affect system behavior or expose sensitive organizational information depending on how work-contract preferences are utilized within the Kimai ecosystem. Although the immediate risk may vary based on specific deployment configurations and the sensitivity of the affected fields, the ability for any authenticated user to modify admin-only settings undermines the integrity of the application's role-based access control model. This could potentially lead to unauthorized changes in billing structures, project assignments, or other contract-related parameters that are critical for accurate time tracking and financial reporting within an organization. The lack of proper validation also sets a precedent where future API endpoints might be similarly vulnerable if developers rely on UI-level restrictions rather than implementing consistent security checks across all entry points.
To mitigate this vulnerability, organizations running Kimai versions between 2.61.0 and 2.63.0 must upgrade to version 2.63.0 or later as soon as possible. The fix in the newer release explicitly addresses this flaw by applying the same permission checks used in the web interface to the API endpoint, ensuring that only users with the appropriate administrative privileges can modify work-contract preferences via any method. In addition to upgrading, administrators should audit recent activity logs for signs of exploitation before patching, looking for unusual PATCH requests targeting user preference endpoints from standard user accounts. Implementing strict input validation and enforcing authorization checks at the service layer rather than relying solely on presentation-layer controls is a fundamental best practice that prevents such inconsistencies in future development cycles.