GHSA-9g2q-w3w2-vf7q: Kimai has Missing Voter Check that Allows Cross-Team Timesheet Manipulation
SummaryAny 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:PoCTested 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:**Response: HTTP 200 — returns full timesheet record including description "Private timesheet - UserA only".**User B deletes User A's timesheet:**Response: HTTP 204 No Content — timesheet permanently deleted.**User B tampers User A's timesheet:**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.ImpactAny 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 historySilently alter timesheet descriptions, hours, and billing flags — forging hours up or down, directly affecting invoicing and payrollEnumerate all timesheet IDs (sequential integers) and access action metadata for arbitrary recordsNo 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 CVEThe 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 usersThese 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.SolutionTeam-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.
CVSS v4.0: 5.7