# 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.

- **Severity:** Critical 10.0 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Aug 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-p68p-fq8j-3639

## 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 (Missing Authentication for Critical Functionality)

## 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.

## Is CVE-2026-81735 being exploited?

There is no known exploitation of CVE-2026-81735 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81735 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-81735 in the wild and no public exploit code.

Affected product: bytedance UI-TARS-desktop. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-81735/ (Markdown: https://insights.sbomify.com/CVE-2026-81735/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81735
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81735
- OSV: https://osv.dev/vulnerability/CVE-2026-81735

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-81735/
Summaries are generated and may contain mistakes; the official description above is the record.