CVE-2026-79537
Received Received - Intake

IDOR Vulnerability in MetaMCP Exposes Tenant Data

Publication date: 2026-09-29

Last updated on: 2026-09-29

Assigner: MITRE

Description
metatool-ai MetaMCP through 2.4.22 contains an insecure direct object reference (IDOR) in the MCP transport session dispatch. The session store (getSession in session-lifetime-manager.ts) is keyed only by the client-supplied mcp-session-id header with no owner, namespace, or endpoint binding, and the per-endpoint authorization middleware validates only the URL endpoint's owner, never the session. An attacker who supplies another tenant's session id " obtained without authentication from GET /metamcp/health/sessions, which discloses active session IDs and namespace UUIDs " can list and execute the victim tenant's private MCP tools and exfiltrate their data using the victim's forwarded credentials.

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Meta Information

Published
2026-09-29
Last Modified
2026-09-29
Generated
2026-09-30
AI Q&A
2026-09-29
EPSS Evaluated
N/A
NVD
CVE-2026-79537
EUVD
EUVD-2026-89362

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
metatool-ai metamcp to 2.4.22 (inc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is an insecure direct object reference (IDOR) in MetaMCP through version 2.4.22. It allows an attacker to access another tenant's private MCP tools and data by using a session ID obtained without authentication from the /metamcp/health/sessions endpoint. The session store is only keyed by a client-supplied header with no owner or namespace binding, and authorization checks only validate the URL endpoint's owner, not the session itself.

Impact Analysis

An attacker could exploit this to list and execute private tools of another tenant, access their sensitive data, and exfiltrate information using the victim's credentials. This could lead to data breaches, unauthorized actions, or loss of confidential information depending on the MCP tools and data involved.

Mitigation Strategies

Update metatool-ai MetaMCP to a version beyond 2.4.22 where the session store is properly secured with owner, namespace, or endpoint binding to prevent unauthorized access.

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