CVE-2026-105789 Microsoft UFO: Arbitrary file write in the Linux MCP `execute_command` tool
An authenticated attacker can overwrite arbitrary files via the Linux MCP execute_command tool, potentially corrupting data or disrupting the service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-105789?
CVE-2026-105789 is a medium-severity path traversal vulnerability in microsoft UFO, published on 6 Oct 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Microsoft UFO is an open-source framework for intelligent automation across devices and platforms. Prior to 3.0.9, the execute_command tool in ufo/client/mcp/http_servers/linux_mcp_server.py treats sort and uniq as read-only commands while the free-form command parameter can select their file-output forms. An authenticated caller can use sort -o or the optional second uniq operand to create or overwrite files writable by the UFO server process without shell metacharacters, because the allowed binary opens the destination itself and the argument policy does not reject the operation. This can corrupt configuration or other writable data and disrupt the service, but the demonstrated primitive does not directly disclose files or establish arbitrary code execution. This issue is fixed in version 3.0.9.
Which versions are affected by CVE-2026-105789?
How do I fix CVE-2026-105789?
No fix has been published for CVE-2026-105789 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-105789 being exploited?
There is no known exploitation of CVE-2026-105789 in the wild and no public exploit code.
Sources
Also known as GHSA-85w2-wggf-rw49.