CVE-2026-105797: SimpleChat: Command injection via authorization-gate ordering flaw (arbitrary process spawn through MCP stdio transport)
SimpleChat is a secure AI conversation application with personal and group workspaces for document-grounded interactions. In versions 0.261.003 and 0.261.027, an authorization ordering flaw in POST /api/user/plugins allows an authenticated low-privileged user to omit the top-level MCP type so that rejectnonadminmcpstdio skips inspection before the type is restored from metadata. The stored personal action can then reach McpPluginFactory.createconnector, and MCPStdioPlugin.connect starts the attacker-selected operating-system process under the application service identity when the action tool is invoked. Exploitation requires personal plugins to be enabled and governance to permit MCP actions, and it can expose or modify secrets and data available to the service or disrupt the service. This issue is fixed in version 0.261.031.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
SimpleChatto a version that resolves this vulnerability.Fixed in 0.261.031
Event History
Frequently Asked Questions
Which deployments are exposed to exploitation?
Deployments running SimpleChat versions 0.261.003 or 0.261.027 are exposed when personal plugins are enabled and governance permits MCP actions. An authenticated low-privileged user is sufficient; no user interaction is required.
What can an attacker do after exploiting the issue?
An attacker can cause the application to start an attacker-selected operating-system process through the MCP stdio transport. The process runs under the application service identity, potentially exposing or modifying data and secrets available to that identity or disrupting the service.
How can we determine whether attempted exploitation is possible in our environment?
Verify whether the deployment uses either affected version, whether personal plugins are enabled, and whether governance allows MCP actions. The vulnerable request path is POST /api/user/plugins, and the malicious personal action triggers process creation when its action tool is invoked.
What is the available remediation?
Upgrade to SimpleChat version 0.261.031, which fixes the authorization ordering flaw. Until patching, disabling personal plugins or preventing MCP actions through governance removes required exploitation conditions.