CriticalVulnerability
GHSA-5c57-rqjx-35g2: Cline Kanban Server has a Cross-Origin WebSocket Hijacking Vulnerability
- Identifiers
- CVE-2026-44211GHSA-5c57-rqjx-35g2
- Published
- Record updated
- Affected
- cline <= 2.13.0
- Fixed in
- No fixed version was stated when the source was last read.
- Known exploitation
- Not listed in the CISA Known Exploited Vulnerabilities catalog at the last check.
- EPSS
- 0.2%
Summary
The kanban npm package, used by the cline CLI, runs a WebSocket server on 127.0.0.1:3484 that does not validate the Origin header on its upgrade requests. Any website a developer visits can connect to the runtime, terminal I/O and control endpoints, leaking workspace paths, task details and agent chat messages. A page can also write input into a running agent's terminal, which the source says leads to remote code execution, or stop active agent sessions. Tested against version 0.1.59.
Mitigation
The source does not state a fix yet. Check the original advisory for updates.
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