Summary
Kimai: Improper Authorization Through Activity Creation with Preset Project Allows Creation Under Unauthorized Projects
Kimai 2.56.0 contains an authenticated improper authorization vulnerability in the preset-project activity creation flow. A user with the generic create_activity permission, but without access to a target project, can still create a new Activity under that unauthorized project by visiting the preset project creation route directly.
This is a persistent cross-project business-object creation issue. The attacker does not need permission to view or edit the target project and only needs to know a valid project.id.
Details
The issue affects the activity creation entry point that accepts a preset project identifier:
GET/POST /en/admin/activity/create/{project}GET/POST /en/admin/project/create/{customer}
In src/Controller/ActivityController.php, the controller checks only the global capability to create activities and does not verify whether the current user is allowed to create an activity under the supplied Project object.
The form and repository path also preserve the preset project instead of rejecting it when the user lacks access. Because the preset project is merged into the candidate set, the final save operation can persist a new Activity under a project that is outside the attacker's authorized project scope.
The same logic applies to the src/Controller/ProjectController.php.
A PoC was provided, but removed for security reasons.
Impact
This vulnerability allows an authenticated user to inject new child business objects into projects outside their authorized scope. An attacker can pollute another team's project configuration, influence later timesheet selection and rate inheritance, and create conditions for downstream business abuse if other users start using the injected activity.
The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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- In
ActivityControllerwe now validate if the project can be edited with[IsGranted('edit', 'project')] - In
ProjectControllerwe now validate if if the customer can be edited with[IsGranted('edit', 'customer')]
Frequently Asked Questions
- What is CVE-2026-52821? CVE-2026-52821 is a medium-severity missing authorization vulnerability in kimai/kimai (composer), affecting versions <= 2.56.0. It is fixed in 2.57.0. The application does not perform an authorization check before performing a sensitive operation.
- Which versions of kimai/kimai are affected by CVE-2026-52821? kimai/kimai (composer) versions <= 2.56.0 is affected.
- Is there a fix for CVE-2026-52821? Yes. CVE-2026-52821 is fixed in 2.57.0. Upgrade to this version or later.
- Is CVE-2026-52821 exploitable, and should I be worried? Whether CVE-2026-52821 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-52821 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-52821? Upgrade
kimai/kimaito 2.57.0 or later.