{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","favicon":"https://feed.craftedsignal.io/favicon-32x32.png","feed_url":"https://feed.craftedsignal.io/products/computer-server--0.3.42/feed.json","home_page_url":"https://feed.craftedsignal.io/","icon":"https://feed.craftedsignal.io/apple-touch-icon.png","items":[{"_cs_actors":[],"_cs_cpes":["cpe:2.3:a:cua:computer-server:*:*:*:*:*:*:*:*"],"_cs_cves":[{"cvss":9.8,"id":"CVE-2026-86121"}],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["computer-server (\u003c 0.3.42)"],"_cs_severities":["critical"],"_cs_tags":["authentication-bypass","remote-code-execution","cve-2026-86121"],"_cs_type":"advisory","_cs_vendors":["Cua"],"content_html":"\u003cp\u003eCua computer-server versions before 0.3.42 suffer from a critical authentication bypass vulnerability. When the application environment is deployed without the CONTAINER_NAME environment variable, the service fails to initialize authentication mechanisms and defaults to binding on all network interfaces. This exposure allows unauthenticated remote actors to interact directly with the application's sensitive API endpoints on TCP port 8000. Successful exploitation provides unauthorized access to the run_command endpoint, enabling arbitrary command execution, unrestricted file system read and write operations, and the ability to initiate interactive PTY shell sessions. Given the service's default network-wide exposure and the severity of the impacted operations, this vulnerability poses a severe risk to host integrity and data confidentiality.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAttacker performs network discovery to identify services listening on TCP port 8000.\u003c/li\u003e\n\u003cli\u003eAttacker probes the discovered target to confirm the presence of the Cua computer-server service.\u003c/li\u003e\n\u003cli\u003eAttacker identifies a misconfigured instance where the CONTAINER_NAME environment variable is missing.\u003c/li\u003e\n\u003cli\u003eAttacker sends an unauthenticated HTTP request to the /run_command endpoint.\u003c/li\u003e\n\u003cli\u003eThe application skips authentication due to the missing environment variable check.\u003c/li\u003e\n\u003cli\u003eAttacker executes arbitrary system commands with the privileges of the application process.\u003c/li\u003e\n\u003cli\u003eAttacker initiates an interactive PTY shell or performs file read/write operations for exfiltration or persistence.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation allows unauthenticated remote attackers to achieve full system compromise. Impact includes arbitrary command execution with application-level privileges, unauthorized access to system files, and the establishment of interactive shell sessions. This can lead to complete data exfiltration, lateral movement within the network, or the deployment of persistent malware.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade Cua computer-server to version 0.3.42 or later immediately to resolve the authentication initialization defect.\u003c/li\u003e\n\u003cli\u003eAudit all running instances of Cua computer-server to verify the presence of the CONTAINER_NAME environment variable.\u003c/li\u003e\n\u003cli\u003eImplement network-level segmentation to restrict access to TCP port 8000 to only trusted management subnets until patching is completed.\u003c/li\u003e\n\u003cli\u003eMonitor webserver logs for HTTP requests directed to the /run_command endpoint from unauthorized IP addresses.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-09-05T11:31:14Z","date_published":"2026-09-05T11:31:14Z","id":"https://feed.craftedsignal.io/briefs/2026-09-cua-authentication-bypass/","summary":"Cua computer-server versions prior to 0.3.42 contain an authentication bypass vulnerability triggered when the CONTAINER_NAME environment variable is unset, allowing unauthenticated remote command execution on TCP port 8000.","title":"Authentication Bypass in Cua computer-server via Environment Variable Misconfiguration","url":"https://feed.craftedsignal.io/briefs/2026-09-cua-authentication-bypass/"}],"language":"en","title":"CraftedSignal Threat Feed - Computer-Server (\u003c 0.3.42)","version":"https://jsonfeed.org/version/1.1"}