OpenCode critical RCE vulnerability fixed under the guise of a "refactor," with no CVE ID, and scanning tools cannot flag affected installations

OpenCode's critical remote code execution vulnerability was fixed with version 1.18.33 released on September 28, but the patch was released under the guise of refactoring the browser launch code, with no security advisory and no CVE requested, so scanners and dependency bots cannot match installations that still need upgrading. According to a Pillar Security report, the vulnerability affects versions 1.0.137 through 1.18.32; a remote MCP server can, during the OAuth handshake, pass a URL into PowerShell on Windows and WSL via the self-chosen authorization_endpoint field, and the $(…) subexpression is treated as code execution, with no additional user interaction required; Pillar assessed CVSS v3.1 as 9.8 Critical. What actually closes the vulnerability is upgrading the open dependency to 11.0.4; scheme validation alone is not enough. According to Pillar's account, Anomaly responded that handling malicious MCP servers is generally outside its threat model.