# CVE-2026-86121: Cua computer-server before 0.3.42 Unauthenticated RCE via Desktop Control

> Unauthenticated attackers can execute arbitrary commands and access files on Cua computer-server when the CONTAINER_NAME environment variable is unset.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-pccw-h89v-h9cj

## What is CVE-2026-86121?

CVE-2026-86121 is a critical authentication bypass vulnerability in trycua cua-computer-server, published on 5 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Cua computer-server versions before 0.3.42 skip authentication when the CONTAINER_NAME environment variable is unset and bind to all interfaces by default, allowing unauthenticated attackers to execute arbitrary commands. Attackers can reach TCP port 8000 to run shell commands via the run_command endpoint, read and write arbitrary files through file operation endpoints, and access interactive PTY shells without authentication.

Weakness: CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-86121?


## How do I fix CVE-2026-86121?

No fix has been published for CVE-2026-86121 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86121 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86121 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86121 and fix it if it is affected.

What it is: CVE-2026-86121 is a critical authentication bypass vulnerability in trycua cua-computer-server, published on 5 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86121 exists.

Affected product: trycua cua-computer-server. 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-2026-86121/ (Markdown: https://insights.sbomify.com/CVE-2026-86121/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86121
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86121
- OSV: https://osv.dev/vulnerability/CVE-2026-86121

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-86121/
Summaries are generated and may contain mistakes; the official description above is the record.