Summary
Claude Code Vulnerable to Command Injection via Piped sed Command Bypasses File Write Restrictions
Claude Code failed to properly validate commands using piped sed operations with the echo command, allowing attackers to bypass file write restrictions. This vulnerability enabled writing to sensitive directories like the .claude folder and paths outside the project scope. Exploiting this required the ability to execute commands through Claude Code with the "accept edits" feature enabled.
Users on standard Claude Code auto-update received this fix automatically. Users performing manual updates are advised to update to the latest version.
Claude Code thanks hackerone.com/nil221 for reporting this issue!
Impact
The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-25723? CVE-2026-25723 is a high-severity improper input validation vulnerability in @anthropic-ai/claude-code (npm), affecting versions < 2.0.55. It is fixed in 2.0.55. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
- Which versions of @anthropic-ai/claude-code are affected by CVE-2026-25723? @anthropic-ai/claude-code (npm) versions < 2.0.55 is affected.
- Is there a fix for CVE-2026-25723? Yes. CVE-2026-25723 is fixed in 2.0.55. Upgrade to this version or later.
- Is CVE-2026-25723 exploitable, and should I be worried? Whether CVE-2026-25723 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-25723 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-25723? Upgrade
@anthropic-ai/claude-codeto 2.0.55 or later.