CVE-2026-55786 Flyto2 Core: Unauthenticated Command Execution via HTTP MCP `execute_module`
Unauthenticated attackers can execute arbitrary OS commands via the HTTP MCP endpoint in Flyto2 Core, leading to potential host compromise.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55786?
CVE-2026-55786 is a high-severity command injection vulnerability in flytohub flyto-core, published on 14 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Flyto2 Core is an execution kernel for automation and AI-agent workflows. From 2.26.2 until 2.26.4, the HTTP MCP POST /mcp route accepts unauthenticated JSON-RPC tools/call requests and forwards execute_module arguments to the module registry without the require_auth dependency used by the REST execution routes. An unauthenticated caller can select sandbox.execute_shell and supply its command parameter, which reaches asyncio.create_subprocess_shell with the privileges of the flyto-core server process. The endpoint is reachable locally under the default loopback binding and becomes network reachable when an operator binds the server to a non-loopback interface, allowing arbitrary OS command execution and potential full host compromise. This issue is fixed in version 2.26.4.
Which versions are affected by CVE-2026-55786?
3 open source packages ship an affected version, including flyto-core.
| Package | Affected | Fixed in |
|---|---|---|
flyto-core PyPI | From 2.26.2 | 2.26.4 |
flyto-core PyPI | From 2.26.2 | 2.26.4 |
flyto-core PyPI | From 2.26.2 | 2.26.4 |
How do I fix CVE-2026-55786?
Upgrade flyto-core to 2.26.4 or later.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-55786 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55786 exists.
Sources
Also known as GHSA-h9f9-h6gm-wc85, PYSEC-2026-2482.