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Improper Authorization in Kimai Timesheet Restart and Duplicate Allows New Timesheets After Project Access Revocation

Moderate severity GitHub Reviewed Published Jun 11, 2026 in kimai/kimai • Updated Jul 14, 2026

Package

composer kimai/kimai (Composer)

Affected versions

<= 2.57.0

Patched versions

2.58.0

Description

Summary

Kimai 2.56.0 contains an authenticated authorization bypass in the timesheet restart and duplicate workflows. After a user loses access to a project, the user can still derive a new timesheet from one of their historical entries and create a new record under that now-unauthorized project and activity combination.

This is a permission revocation bypass with persistent write impact. The issue affects both restart and duplicate, which trust ownership of an old timesheet more than the user's current access to the underlying project, activity, and customer.

Details

The issue affects the following operations:

  • PATCH /api/timesheets/{id}/restart
  • PATCH /api/timesheets/{id}/duplicate

The root cause is that authorization gives too much weight to the fact that the original timesheet belongs to the current user. In src/Voter/TimesheetVoter.php, the *_own_timesheet branch is evaluated before team-based access checks.

The restart/duplicate capability check also verifies only object visibility, not whether the current user still has team-based access to the referenced objects.

In src/API/TimesheetController.php, the restart flow copies the historical project and activity into a new candidate timesheet.

The duplicate flow similarly clones the historical record and saves it.

In src/Timesheet/TimesheetService.php, creation of a new running entry still relies on isGranted('start', $timesheet).

For historical entries that belong to the current user, this logic can still succeed through the *_own_timesheet branch even after project access has been revoked. As a result, normal creation pages correctly stop offering the revoked project, but restart and duplicate can still create new records under it.

The same weakness also affects the Web duplicate flow because the UI path ultimately calls the same save logic in src/Controller/TimesheetAbstractController.php:

A PoC was provided, but removed for security reasons.

Impact

This vulnerability allows a user to keep writing new time entries into a project after project access has been revoked. That undermines administrative access-control changes and can pollute project time tracking, budget calculations, statistics, reports, and invoicing workflows.

Because both restart and duplicate can reuse historical project/activity bindings, old timesheet records effectively become reusable capability tokens that survive later access-control changes. This is not a UI artifact or a caching problem: new database rows are persisted after revocation.

Solution

The metoid TimesheetVoter::canStart() now checks team access for project and activity. This verification is used for new timesheets and also for the duplication and restart workflows.

See https://www.kimai.org/en/security/ghsa-c6w6-57jj-62vh for more information.

References

@kevinpapst kevinpapst published to kimai/kimai Jun 11, 2026
Published to the GitHub Advisory Database Jul 14, 2026
Reviewed Jul 14, 2026
Last updated Jul 14, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity Low
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

EPSS score

Weaknesses

Improper Authorization

The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Learn more on MITRE.

Missing Authorization

The product does not perform an authorization check when an actor attempts to access a resource or perform an action. Learn more on MITRE.

CVE ID

CVE-2026-52822

GHSA ID

GHSA-c6w6-57jj-62vh

Source code

Credits

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