Security Bulletin
Summary
An improper authorization vulnerability in Streamable MCP transport endpoint (/api/v1/mcp/project/{project_id}/streamable) allows unauthenticated attackers to bypass project ownership controls and execute Model Context Protocol (MCP) operations against OAuth-authenticated projects owned by other users. Exploitation enables attackers to: enumerate private MCP tool metadata from other users' OAuth projects, read confidential project files and flow definitions belonging to other users, access user-level files uploaded by the configured superuser, and execute MCP tools anonymously with superuser privileges. The vulnerability is specific to the Streamable transport path and does not affect the properly secured SSE endpoint. Exploitation requires network access to a Langflow instance with MCP Composer enabled and target projects using OAuth/non-apikey authentication mode. No user interaction or authentication is required for exploitation. Four proof-of-concept scenarios were validated demonstrating cross-user tool discovery, cross-user file access, superuser-level file exposure, and anonymous tool execution with superuser context. The vulnerability represents a complete bypass of the application's authorization model for MCP operations in the affected transport path.
Vulnerability Details
CVEID: CVE-2026-7663
DESCRIPTION: Langflow OSS could allow unauthenticated attackers to access protected MCP project resources and execute MCP operations due to improper authorization enforcement in the Streamable MCP transport endpoint.
CWE: CWE-285: Improper Authorization
CVSS Source: IBM
CVSS Base score: 9.1
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N)
Affected Products and Versions
| Affected Product(s) | Version(s) |
| Langflow OSS | 1.0.0 - 1.9.6 |
Remediation/Fixes
IBM strongly recommends addressing the vulnerability now by upgrading Langflow OSS to version 1.10.0
Workarounds and Mitigations
None
Get Notified about Future Security Bulletins
References
Acknowledgement
Change History
23 Jun 2026: Initial Publication
*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.
Disclaimer
According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES ""AS IS"" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.
Document Location
Worldwide
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Document Information
Modified date:
23 June 2026
Initial Publish date:
23 June 2026
UID
ibm17277570