Vulnerability · Published Sep 28, 2026 · Assigned by GitHub_M
CVE-2026-55156Token Optimizer MCP: Unauthenticated Path Traversal in Dashboard Session Log API Endpoints
Medium 5.3
In plain English
A medium-severity path traversal in token-optimizer-mcp from ooples. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | @ooples/token-optimizer-mcp | 5.1.0 | GHSA-76pc-mqxp-3rq5 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| ooples | token-optimizer-mcp | < 5.1.0 |
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N