Auth bypass in Trycua Cua-Computer-Server
CVE-2026-86121
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.011 (65.6th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 66th percentile — 65.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.011 · change: +0.005
Affected products
Weakness classification (CWE)
References
- github.com/trycua/cua (product)
- github.com/trycua/cua/blob/10a2e71792db/libs/python/computer-server/computer_se… (technical-description)
- github.com/trycua/cua/blob/10a2e71792db/libs/python/computer-server/computer_se… (technical-description)
- github.com/trycua/cua/commit/59cf25c0ec54 (patch)
- github.com/trycua/cua/issues/1892 (issue-tracking)
- www.vulncheck.com/advisories/cua-computer-server-before-0.3.42-unauthenticated-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-86121?
- CVE-2026-86121 is a critical-severity vulnerability in Trycua Cua-Computer-Server, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-09-05.
- How severe is CVE-2026-86121?
- Critical severity. CVSS v3 base score is 9.8 out of 10.