Vulnerability Advisory : Cronicle: Non-admin uid/gid injection in create_event/update_event → run-as-arbitrary-user (incl. root) — sibling of CVE-2026-39401 with LOW Attack Complexity

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 `create_events` and `run_events` privileges can inject top-level `uid` and `gid` fields through `/api/app/create_event` or `/api/app/update_event`. 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.