CVE-2026-105789
Microsoft UFO: Arbitrary file write in the Linux MCP `execute_command` tool
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- None
- Integrity
- High
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
5.4
Microsoft UFO: Arbitrary file write in the Linux MCP `execute_command` tool
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.
- Record
CVE-2026-105789- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:L - Weakness
- CWE-88, CWE-184
- Updated
- 2026-11-02
EUVDEUVD-2026-93406
5.4
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.
- Record
EUVD-2026-93406- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:L - Updated
- 2026-11-02
NVD
5.4
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.
- Record
CVE-2026-105789- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:L - Weakness
- CWE-88, CWE-184
- Updated
- 2026-11-02
OSV
5.4
Microsoft UFO: Arbitrary file write in the Linux MCP `execute_command` tool
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.
- Record
CVE-2026-105789- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:L - Weakness
- CWE-184, CWE-88
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-105789 is a medium vulnerability (CVSS 5.4) in Microsoft Ufo, published October 6, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.70%, the 53rd percentile. No source names a fixed version.
References
github.com/microsoft/UFO/security/advisories/GHSA-85w2-wggf-rw49
github.com/microsoft/UFO/pull/349
github.com/microsoft/UFO/commit/4f793622794f5d47810d54bed431c61f6a781dd6
github.com/microsoft/UFO/releases/tag/v3.0.9
github.com/CVEProject/cvelistV5/tree/main/cves/2026/105xxx/CVE-2026-105789.json
nvd.nist.gov/vuln/detail/CVE-2026-105789