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

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Token Optimizer MCP measures token savings per AI coding agent, optimizes context, and shares a live local knowledge graph across 16 CLI clients. Prior to version 5.1.0, 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. This issue has been patched in version 5.1.0.

Source published

28 Sep 2026 17:48:21 UTC

Source modified

28 Sep 2026 18:11:38 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Token Optimizer MCP measures token savings per AI coding agent, optimizes context, and shares a live local knowledge graph across 16 CLI clients. Prior to version 5.1.0, 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. This issue has been patched in version 5.1.0.

Source published

Sep 28, 2026, 5:48:21 PM (timezone not stated)

Source modified

Sep 28, 2026, 6:11:38 PM (timezone not stated)

Observed here

11 Nov 2026 14:02:14 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Token Optimizer MCP measures token savings per AI coding agent, optimizes context, and shares a live local knowledge graph across 16 CLI clients. Prior to version 5.1.0, 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. This issue has been patched in version 5.1.0.

Source published

28 Sep 2026 18:17:23 UTC

Source modified

30 Sep 2026 19:57:08 UTC

Observed here

25 Oct 2026 13:17:34 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

# 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.

Source published

14 Aug 2026 21:43:54 UTC

Source modified

14 Aug 2026 22:11:02 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Publisher rating · MODERATE