A flaw was found in the schedule rrule validation of automation controller. The validation applies several non-anchored regular expressions with lazy wildcard prefixes to the user-supplied rrule value; when the expected DTSTART/RRULE tokens are absent, the matching cost grows quadratically with the length of the value. Any authenticated user can submit a large token-free rrule string through the REST API, including the schedule preview endpoint, which requires no resource-level permissions. Validation runs synchronously in the API web worker, so a single such request occupies a worker for an extended time and repeated requests can exhaust the web worker pool, denying access to the API and web UI until the requests stop. The impact is limited to availability.