CVE-2026-101057: Cleartext Transmission of Sensitive Information in universal-tool-calling-protocol python-utcp
CVE-2026-101057 is a vulnerability in the python-utcp project's utcp-mcp plugin versions before 1.1.3. The plugin connects to HTTP and WebSocket MCP server URLs without enforcing secure URL validation, allowing cleartext transmission of the MCP handshake. This can expose sensitive handshake data to network interception when non-secure HTTP URLs are used in operator-authored configurations. The vulnerability does not affect OAuth2 token credential paths as those were not invoked in affected versions. The issue is fixed in version 1.1.3 by validating server URLs before connection.
AI Analysis
Technical Summary
The utcp-mcp plugin of python-utcp through version 1.1.2 does not enforce the HTTPS/WSS-or-loopback rule on MCP server URLs specified in call templates. This lack of ensure_secure_url validation permits connections to plain HTTP or non-loopback MCP servers, resulting in cleartext transmission of the MCP handshake. Since the mcpServers configuration is operator-authored and the OAuth2 authentication path is not triggered, exploitation is limited. The vulnerability is addressed in version 1.1.3, which adds server URL validation prior to connection attempts.
Potential Impact
An attacker with network access could intercept the MCP handshake transmitted in cleartext when the plugin connects to non-secure HTTP or WebSocket URLs. This exposure could reveal sensitive handshake information. However, practical exploitation is limited because the vulnerable configuration is operator-controlled and OAuth2 credentials are not exposed due to the authentication handler not being invoked in affected versions.
Mitigation Recommendations
Upgrade to utcp-mcp version 1.1.3 or later, which includes validation of MCP server URLs to enforce secure HTTPS/WSS or loopback connections before any connection is made. This fix prevents cleartext transmission of sensitive handshake data.
CVE-2026-101057: Cleartext Transmission of Sensitive Information in universal-tool-calling-protocol python-utcp
Description
CVE-2026-101057 is a vulnerability in the python-utcp project's utcp-mcp plugin versions before 1.1.3. The plugin connects to HTTP and WebSocket MCP server URLs without enforcing secure URL validation, allowing cleartext transmission of the MCP handshake. This can expose sensitive handshake data to network interception when non-secure HTTP URLs are used in operator-authored configurations. The vulnerability does not affect OAuth2 token credential paths as those were not invoked in affected versions. The issue is fixed in version 1.1.3 by validating server URLs before connection.
CVSS v4.0
Score 2.3low
Affected software
universal-tool-calling-protocol
python-utcp
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The utcp-mcp plugin of python-utcp through version 1.1.2 does not enforce the HTTPS/WSS-or-loopback rule on MCP server URLs specified in call templates. This lack of ensure_secure_url validation permits connections to plain HTTP or non-loopback MCP servers, resulting in cleartext transmission of the MCP handshake. Since the mcpServers configuration is operator-authored and the OAuth2 authentication path is not triggered, exploitation is limited. The vulnerability is addressed in version 1.1.3, which adds server URL validation prior to connection attempts.
Potential Impact
An attacker with network access could intercept the MCP handshake transmitted in cleartext when the plugin connects to non-secure HTTP or WebSocket URLs. This exposure could reveal sensitive handshake information. However, practical exploitation is limited because the vulnerable configuration is operator-controlled and OAuth2 credentials are not exposed due to the authentication handler not being invoked in affected versions.
Mitigation Recommendations
Upgrade to utcp-mcp version 1.1.3 or later, which includes validation of MCP server URLs to enforce secure HTTPS/WSS or loopback connections before any connection is made. This fix prevents cleartext transmission of sensitive handshake data.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-27T16:38:56.428Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ab9c994f7a7c54106f51d58
Added to database: 09/28/2026, 01:57:40 UTC
Last enriched: 09/28/2026, 01:58:52 UTC
Last updated: 09/28/2026, 02:07:43 UTC
Views: 4
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