CVE-2026-44211 cline CVE debrief

Who should care

Organizations and developers using Cline as an SDK, IDE extension, or CLI assistant, particularly those exposing Kanban server functionality to network-accessible endpoints. Security teams responsible for securing AI-assisted development tooling and WebSocket-based services.

Technical summary

Cline versions 2.13.0 and prior contain a cross-origin WebSocket hijack vulnerability in the Kanban server component. The flaw enables attackers to establish unauthorized WebSocket connections due to missing authentication (CWE-306) and missing origin validation (CWE-1385). The attack vector is network-based with low complexity, requires user interaction, and results in changed scope with high impacts to confidentiality, integrity, and availability. No patches were available at the time of CVE publication on 2026-06-01.

Defensive priority

CRITICAL

Recommended defensive actions

• Restrict network access to Cline Kanban server instances to trusted origins and implement strict origin validation on all WebSocket endpoints
• Deploy WebSocket connection policies that require authentication and validate the Origin header against an allowlist
• Monitor for anomalous WebSocket connection attempts from unexpected origins or without proper session context
• Subscribe to Cline GitHub security advisories and apply patches immediately upon release
• Review and audit any Cline Kanban server deployments for unauthorized access or data exfiltration indicators

Evidence notes

CVE description confirms affected product (Cline), affected versions (2.13.0 and prior), vulnerability class (cross-origin WebSocket hijack), and absence of patches at publication. CVSS 3.1 vector AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H supports critical severity rating. Source references include GitHub Security Advisory GHSA-5c57-rqjx-35g2. Weaknesses CWE-306 and CWE-1385 are documented in NVD source metadata.

Official resources