CVE-2026-55156 json
Token Optimizer MCP: Unauthenticated Path Traversal in Dashboard Session Log API Endpoints
published 2026-08-14 2 mo ago modified 2026-09-30 39 d ago also GHSA-76pc-mqxp-3rq5 , EUVD-2026-88398
- cvss
- 5.3
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 39%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- npm @ooples/token-optimizer-mcp 5.1.0
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 41 d ago
Exploit prediction
0.45% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/ooples/token-optimizer-mcp/security/advisories/GHSA-76pc-mqxp-3rq5 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
| GitHub | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | @ooples/token-optimizer-mcp | <5.1.0 |
5.1.0 |
Affected products
- ooples token-optimizer-mcp
Classification
- Weakness
-
- CWE-22 Improper Limitation of a Pathname to a Restricted Directory
References
Sources
- CVE List CVE-2026-55156
- GitHub Advisory GHSA-76pc-mqxp-3rq5
- NVD CVE-2026-55156
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