CVE-2026-81735

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.8% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-08-27 11:29 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-08-27 17:21 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-09-23 17:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.8% in the next 30 days (EPSS).
• Severity: 10.0 CRITICAL (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-08-27 17:21 UTC

Last modified

2026-09-23 17:17 UTC

Exploit probability

0.8% · EPSS, next 30 days

Weakness

CWE-306 · Missing authentication

Record status

Deferred

Attack profile CVSS 4.0 · 10.0

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-81735.md and follow it. Check whether this project is affected by CVE-2026-81735. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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