---
id: CVE-2026-81735
title: >-
  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 …
summary: >-
  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 …
severity: critical
cvss: 10
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'
cwe:
  - CWE-306
published: '2026-08-27'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T17:17:43.500'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-81735'
references:
  - url: 'https://github.com/bytedance/UI-TARS-desktop'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/bytedance/UI-TARS-desktop/blob/e9f3387288da4af2ad99972da2ac916cdabce093/packages/agent-infra/mcp-http-server/src/startServer.ts#L263
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/bytedance/UI-TARS-desktop/commit/c2ad42e3eb9b27830db41a3e6f51ca7179d9b168
    label: disclosure@vulncheck.com
  - url: 'https://github.com/bytedance/UI-TARS-desktop/pull/1918'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/ui-tars-desktop-agent-infra-mcp-servers-bind-every-interface-without-authentication-exposing-arbitrary-command-execution
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
epss: 0.00779
epssPercentile: 0.53962
ingestedAt: '2026-09-23T17:28:14.810Z'
vendor: bytedance
product: UI-TARS-desktop
affected:
  - UI-TARS-desktop < c2ad42e3eb9b27830db41a3e6f51ca7179d9b168
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-08-31T18:14:28.159825Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.