CVE-2026-25723 is a vulnerability classified under CWE-20 (Improper Input Validation) and CWE-78 (Improper Neutralization of Special Elements used in an OS Command) affecting anthropics' Claude Code, an agentic coding tool designed to assist in automated code generation and editing. Prior to version 2.0.55, Claude Code failed to properly validate commands that involved piped sed operations combined with the echo command. This improper validation allowed an attacker who could execute commands via the "accept edits" feature to bypass file write restrictions, effectively enabling writes to sensitive directories such as the .claude folder and other paths outside the intended project scope. This bypass could be leveraged to modify or inject malicious files, potentially compromising the integrity and confidentiality of the development environment or enabling further attacks. The vulnerability does not require prior authentication but does require the attacker to have the ability to execute commands through the tool’s editing acceptance feature, which implies some level of user interaction or prior access. The CVSS 4.0 score of 7.7 (high severity) reflects the network attack vector, low attack complexity, partial attack prerequisites, and high impact on confidentiality, integrity, and availability. The issue was publicly disclosed on February 6, 2026, and has been addressed in version 2.0.55 of Claude Code. No known exploits have been reported in the wild, but the potential for abuse exists in environments where the tool is used with the vulnerable versions.

For European organizations, the impact of this vulnerability can be significant, especially for software development teams relying on Claude Code for automated coding assistance. Unauthorized writes to sensitive directories could lead to the insertion of malicious code, backdoors, or tampering with configuration files, potentially compromising the entire software supply chain or development lifecycle. This could result in intellectual property theft, disruption of development processes, or introduction of vulnerabilities into production code. Organizations in sectors with high regulatory requirements such as finance, healthcare, and critical infrastructure could face compliance violations and reputational damage if exploited. Furthermore, the ability to write outside the project scope increases the risk of lateral movement within internal networks, potentially escalating the attack impact beyond the initial compromise. Given the network-based attack vector and ease of exploitation once command execution is possible, the threat is particularly relevant for collaborative environments or cloud-based development platforms where multiple users interact with the tool.

To mitigate this vulnerability, European organizations should immediately upgrade all instances of Claude Code to version 2.0.55 or later, where the input validation flaw has been patched. Additionally, organizations should restrict the use of the "accept edits" feature to trusted users only and implement strict access controls to limit who can execute commands through Claude Code. Monitoring and logging command execution activities within the tool can help detect suspicious behavior early. Employing application whitelisting and sandboxing techniques around the development environment can reduce the risk of unauthorized file writes affecting critical system areas. Regularly auditing the .claude folder and other sensitive directories for unauthorized changes can help identify exploitation attempts. Finally, integrating secure coding and code review practices to detect anomalous code changes introduced via automated tools will further reduce risk.