CVE-2026-55156

36th percentile - higher than 36% of all known CVEs

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.

An unauthenticated attacker can read arbitrary .jsonl files on the server, potentially leading to disclosure of sensitive data, including session data or configuration data.

It is recommended to immediately update token-optimizer-mcp to version 5.1.0 or later, which includes the fix.