Vulnerability · Published Sep 27, 2026 · Assigned by VulnCheck

CVE-2026-101057utcp-mcp before 1.1.3 SSRF via unvalidated MCP server URL

Low 3.1

In plain English

A low-severity security flaw in python-utcp from universal-tool-calling-protocol. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities).

Severity (CVSS 3.1)3.1Low

Exploit odds (30 days)0.1%top 98.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
universal-tool-calling-protocol	python-utcp	0 – before 1.1.3

Weakness: CWE-319 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N

References

GitHub Security Advisory (GHSA-qwr9-cj2c-v3fv) vendor-advisory
VulnCheck Advisory: utcp-mcp before 1.1.3 SSRF via unvalidated MCP server URL third-party-advisory