GHSA-9G2Q-W3W2-VF7Q

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 "team" support later on
if ($subject->getUser()?->getId() === $user->getId()) {
    $permission .= 'own';
} else {
    $permission .= 'other';
}

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: <userb_api_token>

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: <userb_api_token>

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: <userb_api_token>
Content-Type: application/json

{"begin":"2026-03-24T08:00:00","end":"2026-03-24T18:00:00","project":1,"activity":1,"description":"TAMPERED","exported":false,"billable":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.

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.

Any authenticated user with ROLE_TEAMLEAD or above can:

1. Permanently delete timesheets belonging to any user system-wide, destroying billable hours, payroll data, and project billing history
2. Silently alter timesheet descriptions, hours, and billing flags, forging hours up or down, directly affecting invoicing and payroll
3. 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.

The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.

Kodem intelligence

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.

1. What is GHSA-9G2Q-W3W2-VF7Q? GHSA-9G2Q-W3W2-VF7Q is a medium-severity incorrect authorization vulnerability in kimai/kimai (composer), affecting versions <= 2.55.0. It is fixed in 2.56.0. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
2. Which versions of kimai/kimai are affected by GHSA-9G2Q-W3W2-VF7Q? kimai/kimai (composer) versions <= 2.55.0 is affected.
3. Is there a fix for GHSA-9G2Q-W3W2-VF7Q? Yes. GHSA-9G2Q-W3W2-VF7Q is fixed in 2.56.0. Upgrade to this version or later.
4. Is GHSA-9G2Q-W3W2-VF7Q exploitable, and should I be worried? Whether GHSA-9G2Q-W3W2-VF7Q 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
5. What actually determines whether GHSA-9G2Q-W3W2-VF7Q 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.
6. How do I fix GHSA-9G2Q-W3W2-VF7Q? Upgrade kimai/kimai to 2.56.0 or later.