CVE-2025-55284 is a high-severity OS command injection vulnerability (CWE-78) affecting the anthropics 'claude-code' agentic coding tool in versions prior to 1.0.4. Claude Code is designed to assist with coding tasks by executing commands, but due to an overly broad allowlist of safe commands, attackers can bypass confirmation prompts intended to prevent unauthorized actions. Specifically, an attacker who can inject untrusted content into a Claude Code context window can exploit this flaw to read arbitrary files on the host system and exfiltrate their contents over the network without user confirmation. This vulnerability arises from improper neutralization of special elements used in OS commands, allowing malicious input to be executed directly by the operating system shell. The vulnerability requires no privileges or authentication and no user interaction beyond supplying malicious input into the context window. The CVSS 4.0 base score is 7.1, reflecting network attack vector, low attack complexity, no privileges or authentication required, but requiring user interaction (input of malicious content). The impact is primarily on confidentiality, as attackers can read sensitive files and send data externally. Integrity and availability impacts are not indicated. The vulnerability has been fixed in version 1.0.4, and all users on standard auto-update paths have been forced to update to versions 1.0.24 or later, which are not vulnerable. There are no known exploits in the wild at this time. The vulnerability is significant because it allows stealthy data exfiltration from systems running vulnerable versions of Claude Code, especially in environments where untrusted input can be injected into the tool's context window.

For European organizations, this vulnerability poses a risk of confidential data leakage if Claude Code is used in development or operational environments where untrusted input can be introduced. Sensitive source code, configuration files, or credentials could be exposed, leading to intellectual property theft or further compromise. Since Claude Code is an agentic coding assistant, organizations relying on it for automation or coding tasks may inadvertently allow attackers to bypass security controls. The lack of required privileges or authentication lowers the barrier for exploitation, increasing risk. However, the forced update and deprecation of vulnerable versions mitigate widespread impact. Organizations that have not updated or use customized deployments without auto-update remain at risk. The impact is more pronounced in sectors with stringent data protection requirements such as finance, healthcare, and critical infrastructure within Europe, where data breaches can lead to regulatory penalties under GDPR and other laws.

1. Ensure all deployments of Claude Code are updated to version 1.0.4 or later, preferably the latest stable release, to incorporate the fix for this vulnerability. 2. Disable or restrict the ability to inject untrusted content into Claude Code context windows, implementing strict input validation and sanitization where possible. 3. Monitor network traffic for unusual outbound connections or data transfers originating from systems running Claude Code, as exfiltration is a key exploitation vector. 4. Employ application whitelisting and endpoint detection and response (EDR) tools to detect and block unauthorized command execution attempts. 5. Conduct security awareness training for developers and users of Claude Code to recognize suspicious behavior and understand the importance of applying updates promptly. 6. Review and harden configurations of Claude Code deployments, limiting network access and permissions to the minimum necessary. 7. Implement logging and auditing of Claude Code activities to enable forensic analysis in case of suspected exploitation.