GHSA-9xpg-9w3g-mpwj: Cronicle: Non-admin uid/gid injection in create_event/update_event → run-as-arbitrary-user (incl. root) — sibling of CVE-2026-39401

Cronicle is a multi-server task scheduler and runner, with a web based front-end UI. Prior to 0.9.121, a non-administrator user or scoped API key with createevents and runevents privileges can inject top-level uid and gid fields through /api/app/createevent or /api/app/updateevent. In lib/api.js, requireValidEventData uses validateOptionalParams as a partial allow-list that silently passes unknown keys, storing the injected fields verbatim. In lib/job.js, launchJob copies the whole event into the job, and a plugin uid overrides the event uid only when the plugin defines one. The default shellplug and urlplug plugins do not define a uid, so the event-controlled identity survives into child-process launch. On a root-daemon installation, this lets a low-privileged user run jobs as arbitrary users, including root, bypassing the otherwise administrator-only run-as-user control. This API-side event injection is distinct from the job-output uid/gid injection addressed by CVE-2026-39401. This issue is fixed in version 0.9.121.