Medium severity · published Sep 28, 2026
CVE-2026-55156
Token Optimizer MCP: Unauthenticated Path Traversal in Dashboard Session Log API Endpoints
5.3
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 39% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
TO
token-optimizer-mcp · ooples
< 5.1.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55156
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-55156
x_refsource_CONFIRM
https://github.com/ooples/token-optimizer-mcp/security/advisories/GHSA-76pc-mqxp-3rq5
x_refsource_MISC
https://github.com/ooples/token-optimizer-mcp/commit/b4ee96dac799cbfba0a9f9c17844ce9d613cbcc7
x_refsource_MISC
https://github.com/ooples/token-optimizer-mcp/releases/tag/v5.1.0
More from token-optimizer-mcp
8.4
CVE-2026-55157
Token Optimizer MCP: OS command injection in smart_user via username in get-user-info