CVE-2026-105797 Command injection in simplechat
Authenticated low-privileged users can execute arbitrary OS commands via MCP stdio transport due to an authorization ordering flaw in SimpleChat.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-105797?
CVE-2026-105797 is a high-severity command injection vulnerability in microsoft simplechat, published on 6 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-105797?
How do I fix CVE-2026-105797?
No fix has been published for CVE-2026-105797 yet. Limit exposure of the affected software until one is available.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-105797 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-105797 exists.
Sources
Also known as GHSA-h4mw-qw8m-5x4j.