CVE-2023-26114 in code-server
Summary
by MITRE • 03/23/2023
Versions of the package code-server before 4.10.1 are vulnerable to Missing Origin Validation in WebSockets handshakes. Exploiting this vulnerability can allow an adversary in specific scenarios to access data from and connect to the code-server instance.
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Analysis
by VulDB Data Team • 04/13/2023
The vulnerability identified as CVE-2023-26114 affects the code-server package version 4.10.1 and earlier, representing a critical weakness in WebSocket handshake validation mechanisms. This issue stems from insufficient origin validation during WebSocket connections, creating a pathway for malicious actors to exploit the system under specific conditions. The vulnerability resides in the WebSocket protocol implementation where the server fails to properly verify the origin of incoming connections, allowing unauthorized entities to establish WebSocket sessions that should otherwise be restricted.
The technical flaw manifests in the WebSocket handshake process where the server does not adequately validate the Origin header or other identifying parameters that should confirm the legitimacy of connection requests. This missing validation step creates a scenario where an attacker can craft malicious WebSocket connections that bypass normal access controls. The vulnerability is categorized under CWE-284, which specifically addresses improper access control in web applications, and aligns with ATT&CK technique T1071.004 for application layer protocol usage. When exploited, this vulnerability enables adversaries to establish unauthorized WebSocket connections to the code-server instance, potentially gaining access to sensitive data and system resources.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it creates a persistent threat vector that can be leveraged for further exploitation. Attackers can use this weakness to establish covert communication channels with the code-server, potentially exfiltrating data, executing commands, or using the compromised instance as a pivot point for attacking other systems within the network. The specific nature of the vulnerability means that exploitation requires particular network conditions and may not be universally applicable, but when successful, it provides attackers with direct access to the code-server environment and its associated resources.
Mitigation strategies should focus on immediate patching to version 4.10.1 or later where the origin validation has been properly implemented. Organizations should also implement additional network-level controls including WebSocket traffic filtering and monitoring for suspicious connection patterns. The implementation of proper origin validation in WebSocket handshakes represents a fundamental security requirement that should be enforced at multiple levels including application code, reverse proxies, and network firewalls. Security teams should conduct thorough audits of all WebSocket implementations and ensure that proper validation mechanisms are in place to prevent similar vulnerabilities from emerging in other components of the system architecture.