CVE-2026-86121: Missing Authentication for Critical Function in trycua cua-computer-server
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.
CVSS v4.0
Score 9.3critical
Affected software
trycua
cua-computer-server
pkg:github/cua-computer-serverRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in trycua cua-computer-server versions prior to 0.3.42 arises from missing authentication for critical functions when the CONTAINER_NAME environment variable is not set. In this state, the server binds to all interfaces and does not require authentication for access. Attackers can exploit this by connecting to TCP port 8000 and using the run_command endpoint to execute shell commands, file operation endpoints to read and write arbitrary files, and gain interactive PTY shell access without any authentication.
Potential Impact
Unauthenticated remote attackers can execute arbitrary commands, manipulate files, and obtain interactive shell access on affected cua-computer-server instances. This leads to full compromise of the server, potentially allowing complete control over the host system.
Mitigation Recommendations
A fix is available in cua-computer-server version 0.3.42. Users should upgrade to version 0.3.42 or later to remediate this vulnerability. Until upgraded, ensure the CONTAINER_NAME environment variable is properly set to avoid the server binding to all interfaces without authentication.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-05T01:59:22.753Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a9bed73acd9273b49b1c674
Added to database: 09/05/2026, 10:22:43 UTC
Last enriched: 09/25/2026, 02:47:30 UTC
Last updated: 10/20/2026, 18:48:24 UTC
Views: 132
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