Unauthenticated HTTP Service in OpenCode Leads to RCE: The Security Red Line for Open-Source AI Coding Agents

### CVE-2026-22812 Disclosure: Versions of OpenCode prior to 1.0.216 automatically start an unauthenticated HTTP service upon launch, which defaults to ports starting at 4096 and exposes interfaces for shell execution, PTY access and arbitrary file reading. Combined with permissive CORS policies, both local processes and malicious web pages can achieve remote code execution (RCE). This vulnerability has a CVSS score of 8.8 and was fixed in version 1.0.216. This article sorts out the cause of the vulnerability, the Proof-of-Concept (PoC) attack path, and the industry background of the Hugging Face Agent intrusion, and provides suggestions for upgrading and secure Agent security design.