What’s Vulnerable › Vulnerabilities

CVE-2026-105797: SimpleChat: Command injection via authorization-gate ordering flaw (arbitrary process spawn through MCP stdio transport)

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-06 · updated 2026-10-06
• Weakness: CWE-78

Description

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 _reject_non_admin_mcp_stdio skips inspection before the type is restored from metadata. The stored personal action can then reach McpPluginFactory.create_connector, 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 products

• microsoft simplechat: before 0.261.031

References

• https://github.com/microsoft/simplechat/commit/73ff7d6998dc4827a0f6ba002386275a7c1ec804
• https://github.com/microsoft/simplechat/security/advisories/GHSA-h4mw-qw8m-5x4j
• https://github.com/microsoft/simplechat/security/advisories/GHSA-h4mw-qw8m-5x4j

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