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2.3

CVE-2026-101057: python-utcp MCP plugin can expose internal traffic

CVE-2026-101057 · published 22 days ago
Summary

The MCP plugin used by python-utcp may connect to a server URL that is not forced to use HTTPS or a local address. If a plain HTTP address is configured, the handshake can be intercepted or seen on the network, potentially revealing internal communications. Update to version 1.1.3 or later, which adds a check to require secure URLs, or change all configurations to use HTTPS or secure local connections.

What to do
  • Update universal-tool-calling-protocol python-utcp to version 1.1.3 or later.
Affected software
VendorProductAffected versions
universal-tool-calling-protocol python-utcp < 1.1.3
Original advisory text
utcp-mcp before 1.1.3 SSRF via unvalidated MCP server URL
utcp-mcp (the MCP plugin of python-utcp) through 1.1.2 connects to the HTTP and WebSocket MCP server URLs given in a call template's mcpServers configuration without the ensure_secure_url validation that the HTTP-family plugins apply, so the HTTPS/WSS-or-loopback rule is not enforced. A call template naming a plain-HTTP, non-loopback MCP server URL is dialed as configured, exposing the MCP handshake to network interception and permitting cleartext connections to internal hosts. The mcpServers configuration is operator-authored rather than remote data, and the connection is an MCP handshake rather than an arbitrary request returning a body, which limits practical exploitation; the OAuth2 token_url credential path described in the original report was not reachable in the affected versions, because the OAuth2 handler was never invoked and the call template's auth field was not read. Fixed in utcp-mcp 1.1.3, which validates server URLs before any connection is made.
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker partial control
Severity
2.3 Low
Exploitation
<1% chance of attack within 30 days
Type
CWE-319Cleartext Transmission of Sensitive Information
Timeline
Published27 Sep 2026
Updated1 Oct 2026
First seen27 Sep 2026
Sources
CVE-2026-101057 · MITRE
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