GHSA-4fm3-ggg2-c6qx AzuraCast's Missing RequireInternalConnection on Liquidsoap API Allows Low-Privilege Metadata Injection and Broadcast Disruption
SummaryThe `/api/internal/{station_id}/liquidsoap/{action}` endpoint is accessible from the public web interface because it lacks the `RequireInternalConnection` middleware that protects other internal endpoints (`/sftp-auth`, `/sftp-event`). Combined with a logic flaw where the `$asAutoDj` flag is set based on the *presence* of the `X-Liquidsoap-Api-Key` header rather than its *validated value*, any user with the basic `View` station permission can invoke privileged Liquidsoap commands — injecting arbitrary now-playing metadata visible to all listeners, disrupting live broadcast tracking, and disclosing absolute filesystem paths.Details**Issue 1: Missing RequireInternalConnection middleware**In `backend/config/routes/api_internal.php`, the liquidsoap route group (lines 17-21) lacks the `RequireInternalConnection` middleware:Compare with sftp endpoints that correctly apply it:The nginx config (`util/docker/web/nginx/azuracast.conf.tmpl`) only sets the `IS_INTERNAL` FastCGI parameter on the internal port 6010 listener (line 44), not on the public-facing server block (ports 80/443). Without the middleware, the endpoint is fully accessible from the public internet.**Issue 2: `$asAutoDj` derived from header presence, not validated value**In `backend/src/Controller/Api/Internal/LiquidsoapAction.php`:When a user authenticates via session/API key and has `StationPermissions::View`, the ACL check passes and the adapter API key is never validated. But `$asAutoDj` is already `true` from line 34 because the header is present (with any arbitrary value).**Affected commands:**`FeedbackCommand` (`backend/src/Radio/Backend/Liquidsoap/Command/FeedbackCommand.php:36`): Guard `if (!$asAutoDj) return false;` bypassed — creates SongHistory records and forces NowPlaying cache updates`DjOffCommand` (`backend/src/Radio/Backend/Liquidsoap/Command/DjOffCommand.php:24`): Guard bypassed — calls `$this->streamerRepo->onDisconnect($station)` which ends all active broadcasts and sets `$station->is_streamer_live = false``DjOnCommand` (`backend/src/Radio/Backend/Liquidsoap/Command/DjOnCommand.php:31`): Guard bypassed — calls `$this->streamerRepo->onConnect($station, $user)` with attacker-controlled username`CopyCommand` (`backend/src/Radio/Backend/Liquidsoap/Command/CopyCommand.php:18`): No `$asAutoDj` guard at all — returns absolute filesystem paths via `$mediaFs->getLocalPath($uri)`PoC**Prerequisites:** A user account with `StationPermissions::View` on station ID 1 (the lowest station-level permission). Obtain a session cookie or API key for this user.**1. Inject arbitrary now-playing metadata (FeedbackCommand):**Expected: Should reject — user does not have the adapter API key.
Actual: Returns `true`. The injected artist/title appears in `/api/nowplaying/1` for all listeners.**2. Disrupt live broadcast (DjOffCommand):**Expected: Should reject.
Actual: Returns `true`. All active broadcast records for the station are terminated (`timestampEnd` set), `is_streamer_live` set to `false`, and `current_streamer` cleared.**3. Disclose filesystem paths (CopyCommand):**Expected: Should reject — this is an internal-only endpoint.
Actual: Returns `{"uri":"/var/azuracast/stations/1/media/test.mp3","isTemp":false}` — disclosing the absolute filesystem path of the station's media storage.ImpactAny user with the basic `StationPermissions::View` permission (the lowest station-level role, commonly assigned to DJs and collaborators) can:**Inject arbitrary now-playing metadata** visible to all listeners via the public NowPlaying API and any connected players/widgets. This poisons the song history database and triggers cache updates that propagate the false data to all consumers.**Disrupt live broadcasts** by terminating all active broadcast records and marking the station as having no live streamer, even when a DJ is actively broadcasting. This affects broadcast recording and live-DJ tracking.**Fake DJ connections** with arbitrary usernames via the `djon` command, polluting streamer logs and potentially interfering with DJ scheduling.**Disclose absolute filesystem paths** of the station's media storage directory via the `cp` command (no `$asAutoDj` guard required), which aids further attacks against the server.Recommended Fix**Fix 1: Add `RequireInternalConnection` middleware to the liquidsoap route group.**In `backend/config/routes/api_internal.php`, add the middleware to the station group:**Fix 2: Validate the API key value before setting `$asAutoDj`.**In `backend/src/Controller/Api/Internal/LiquidsoapAction.php`, move `$asAutoDj` assignment after key validation:Both fixes should be applied. Fix 1 is the primary defense (defense in depth — this endpoint should never be publicly accessible). Fix 2 corrects the logic flaw so that `$asAutoDj` is only `true` when the adapter API key is actually valid, regardless of how authentication was performed.
CVSS v3.1 score: 6.3