CVE-2026-81735 Missing authorization in UI-TARS-desktop
Unauthenticated remote attackers can execute arbitrary commands and read/write files via exposed MCP servers due to missing authentication and default binding to all interfaces.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-81735?
CVE-2026-81735 is a critical missing authorization vulnerability in bytedance UI-TARS-desktop, published on 27 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-306
Which versions are affected by CVE-2026-81735?
How do I fix CVE-2026-81735?
No fix has been published for CVE-2026-81735 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-81735 being exploited?
There is no known exploitation of CVE-2026-81735 in the wild and no public exploit code.
Sources
Also known as GHSA-p68p-fq8j-3639.