ByteDance UI-TARS-desktop mcp-http-server startServer.ts startSseAndStreamableHttpMcpServer os command injection

Summaryinfo

A vulnerability was found in ByteDance UI-TARS-desktop. It has been declared as critical. This impacts the function startSseAndStreamableHttpMcpServer of the file startServer.ts of the component mcp-http-server. Executing a manipulation can lead to os command injection. This vulnerability is tracked as CVE-2026-81735. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability classified as critical was found in ByteDance UI-TARS-desktop (version now known). This vulnerability affects the function startSseAndStreamableHttpMcpServer of the file startServer.ts of the component mcp-http-server. The manipulation with an unknown input leads to a os command injection vulnerability. The CWE definition for the vulnerability is CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

startServer.ts in the mcp-http-server package of UI-TARS-desktop defaulted its listen address to '::' when no host was given, so startSseAndStreamableHttpMcpServer bound the Streamable HTTP and SSE MCP transports to every interface, and its authentication middleware was optional: middlewares are applied only when a caller supplies them. The @agent-infra/mcp-server-commands and @agent-infra/mcp-server-filesystem entry points call startSseAndStreamableHttpMcpServer with a host and port alone and pass no middleware, so neither server required a credential. The commands server exposes a run_command tool that hands its caller-supplied command string to promisify(child_process.exec), so any unauthenticated client able to reach the port could run arbitrary commands as the user running the server, and the filesystem server exposed its file read and write tools on the same terms. The listen default became 127.0.0.1 in commit c2ad42e3eb9b27830db41a3e6f51ca7179d9b168; the package version stayed at 1.2.4 across that change, so the boundary is the commit rather than a release.

The advisory is available at github.com. This vulnerability was named CVE-2026-81735 since 08/27/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1202 by the MITRE ATT&CK project.

Applying the patch c2ad42e3eb9b27830db41a3e6f51ca7179d9b168 is able to eliminate this problem.

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Productinfo

Vendor

• ByteDance

Name

• UI-TARS-desktop

Website

• Product: https://github.com/bytedance/UI-TARS-desktop/

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