CVE-2025-54795: Anthropic Claude Code RCE Vulnerability

CVE-2025-54795 Overview

CVE-2025-54795 is a command injection vulnerability (CWE-78) affecting Anthropic Claude Code, an agentic coding tool. In versions below 1.0.20, an error in command parsing makes it possible to bypass the Claude Code confirmation prompt to trigger execution of an untrusted command. Reliably exploiting this requires the ability to add untrusted content into a Claude Code context window. This vulnerability has been addressed in version 1.0.20.

Critical Impact

Successful exploitation allows attackers to bypass security confirmation prompts and execute arbitrary commands on the target system, potentially leading to complete system compromise, data exfiltration, or lateral movement within the network.

Affected Products

• Anthropic Claude Code versions prior to 1.0.20
• Claude Code Node.js implementations (cpe:2.3:a:anthropic:claude_code:*:*:*:*:*:node.js:*:*)

Discovery Timeline

• 2025-08-05 - CVE-2025-54795 published to NVD
• 2025-10-24 - Last updated in NVD database

Technical Details for CVE-2025-54795

Vulnerability Analysis

This vulnerability stems from improper command parsing logic within Claude Code's execution flow. When Claude Code processes user inputs and prepares to execute system commands, a confirmation prompt normally provides a security checkpoint requiring user approval before potentially dangerous operations proceed. However, a flaw in the parsing mechanism allows specially crafted input to circumvent this protective measure entirely.

The vulnerability requires an attacker to inject untrusted content into the Claude Code context window. In agentic coding environments, context windows can aggregate content from multiple sources including project files, documentation, external APIs, and user inputs. If any of these sources contain malicious payloads, the command parsing error can be triggered to bypass confirmation and execute arbitrary commands.

Root Cause

The root cause is classified as CWE-78 (Improper Neutralization of Special Elements used in an OS Command), commonly known as OS Command Injection. The command parsing logic fails to properly validate and sanitize command structures before determining whether user confirmation is required. This creates a gap where maliciously formatted commands can slip through the confirmation check while still being valid for execution.

Attack Vector

The attack vector is network-based, requiring user interaction. An attacker must first establish a way to inject untrusted content into the Claude Code context window. This could be achieved through:

• Malicious content embedded in project files that Claude Code ingests
• Poisoned external documentation or code snippets
• Compromised API responses that feed into the context
• Social engineering tactics to get users to paste malicious content

Once the malicious content reaches the context window, the parsing error allows commands to execute without the expected confirmation dialog, giving the attacker arbitrary command execution capabilities on the host system.

The vulnerability mechanism involves crafted input that exploits inconsistencies in how the confirmation prompt evaluates command safety versus how the execution engine interprets commands. For detailed technical analysis, refer to the GitHub Security Advisory GHSA-x56v-x2h6-7j34.

Detection Methods for CVE-2025-54795

Indicators of Compromise

• Unexpected command executions occurring without corresponding confirmation prompt logs
• Unusual process spawning from Claude Code parent processes
• Presence of suspicious content within Claude Code context or session logs
• Network connections or file system modifications that were not user-initiated

Detection Strategies

• Monitor Claude Code process trees for child processes that indicate command execution without matching confirmation events
• Implement logging on all Claude Code sessions to correlate user confirmations with actual command executions
• Deploy endpoint detection rules to flag command execution patterns typical of injection attacks
• Audit project files and external content sources for potentially malicious payloads

Monitoring Recommendations

• Enable verbose logging in Claude Code installations to capture full context window contents
• Set up alerts for version 1.0.19 and below installations within your environment
• Monitor for behavioral anomalies such as commands executing with elevated privileges or accessing sensitive directories
• Review and baseline normal Claude Code usage patterns to identify deviations

How to Mitigate CVE-2025-54795

Immediate Actions Required

• Upgrade Claude Code to version 1.0.20 or later immediately
• Audit recent Claude Code session logs for any signs of exploitation
• Review all untrusted content sources that may feed into Claude Code context windows
• Restrict Claude Code execution permissions using principle of least privilege

Patch Information

Anthropic has released version 1.0.20 which addresses this command parsing vulnerability. The fix ensures proper validation of command structures before bypass of confirmation prompts. Users should update to the latest version through their standard package management workflow. For additional details, consult the GitHub Security Advisory.

Workarounds

• Limit Claude Code's ability to execute system commands by restricting its runtime environment
• Manually review all external content before allowing it into Claude Code context windows
• Run Claude Code in a sandboxed or containerized environment to limit blast radius of potential exploitation
• Implement network segmentation to contain potential lateral movement if exploitation occurs

# Upgrade Claude Code to patched version
npm update @anthropic/claude-code@1.0.20

# Verify installed version
npm list @anthropic/claude-code

# Alternative: Restrict command execution permissions in containerized environments
# Run Claude Code with limited shell access