An undocumented flaw in geelen/mcp-remote between versions 0.1.16 and 0.1.38 permits a remote attacker to run arbitrary code by tampering with the getServerUrlHash function located in src/lib/utils.ts. This function processes data from the server URL to produce a hash, and the implementation is vulnerable to improper validation, allowing crafted input to trigger code execution. The weakness is an example of CWE‑328.

The vulnerability affects Geelen’s MCP‑Remote, a lightweight server communication library, in all releases from 0.1.16 through 0.1.38. Users running any of these versions are exposed unless they upgrade.

Remote code execution is a severe outcome, permitting full control of the host system. The CVSS score is 9.8 and the EPSS score is < 1%; KEV contains no entry, so the exact exploitation probability is unknown; however, given the nature of the flaw and the lack of mitigations, the risk is considered high. The likely attack vector is a remote invocation of the vulnerable function, possibly via crafted URLs to the MCP‑Remote server. Based on the description, it is inferred that sending specially formed server URLs initiates the malicious code path.