CVE-2025-55284: Claude Code Auth Bypass Vulnerability

CVE-2025-55284 Overview

CVE-2025-55284 is a command injection vulnerability (CWE-78) affecting Anthropic Claude Code, an agentic coding tool. Prior to version 1.0.4, it was possible to bypass the Claude Code confirmation prompts to read a file and then send file contents over the network without user confirmation due to an overly broad allowlist of safe commands.

Critical Impact

Attackers who can inject untrusted content into a Claude Code context window can bypass security confirmation prompts, enabling unauthorized file reads and data exfiltration over the network without user awareness.

Affected Products

• Anthropic Claude Code versions prior to 1.0.4
• Claude Code for Node.js installations not using auto-update

Discovery Timeline

• 2025-08-16 - CVE-2025-55284 published to NVD
• 2025-10-24 - Last updated in NVD database

Technical Details for CVE-2025-55284

Vulnerability Analysis

The vulnerability exists in Claude Code's command execution permission system. The application maintains an allowlist of commands considered "safe" that can execute without explicit user confirmation. This allowlist was overly permissive, allowing certain combinations of commands to bypass the security confirmation prompts entirely.

Reliably exploiting this vulnerability requires the ability to add untrusted content into a Claude Code context window. Once malicious content is injected into the context, an attacker can leverage the overly broad command allowlist to read sensitive files from the local system and transmit their contents to an external network endpoint—all without triggering the security confirmation that users expect to see for such operations.

The vulnerability is categorized as CWE-78 (Improper Neutralization of Special Elements used in an OS Command), indicating that the root cause involves insufficient validation or restriction of commands that can be executed through the system.

Root Cause

The root cause of CVE-2025-55284 stems from an overly broad allowlist implementation in Claude Code's security model. The allowlist was designed to enable seamless execution of common, safe operations without interrupting the user's workflow with confirmation dialogs. However, the criteria for determining which commands were "safe" did not adequately account for command chaining or specific command combinations that could be abused to read files and transmit data externally.

This design flaw allowed attackers to construct command sequences that individually appeared benign but, when combined, could perform unauthorized file access and network data transmission operations.

Attack Vector

The attack vector requires network access with user interaction, as the attacker must first inject malicious content into a Claude Code context window. This could occur through:

1. A user opening a maliciously crafted project or file
2. Content injection through shared codebases or repositories
3. Social engineering to convince users to paste malicious content

Once malicious content is present in the context window, the attacker can craft commands that exploit the overly permissive allowlist to read local files and exfiltrate their contents to attacker-controlled servers without displaying any confirmation prompt to the user.

The vulnerability mechanism involves bypassing the confirmation prompt system by leveraging commands that fall within the "safe" allowlist but can be combined or parameterized to perform sensitive operations. For technical implementation details, refer to the GitHub Security Advisory.

Detection Methods for CVE-2025-55284

Indicators of Compromise

• Unexpected outbound network connections from Claude Code processes to unknown external endpoints
• Unusual file read operations performed by Claude Code, especially targeting sensitive configuration files, credentials, or proprietary source code
• Claude Code executing network-capable commands without corresponding user confirmation in logs
• Evidence of context manipulation or injection of suspicious content into Claude Code sessions

Detection Strategies

• Monitor Claude Code process activity for unexpected command executions, particularly those involving file reads followed by network operations
• Implement network traffic analysis to identify data exfiltration patterns from Claude Code processes
• Review Claude Code logs for command sequences that bypass expected confirmation prompts
• Deploy endpoint detection rules to alert on Claude Code versions prior to 1.0.4

Monitoring Recommendations

• Configure SentinelOne Singularity platform to monitor for suspicious process behavior associated with Claude Code
• Implement network segmentation and monitoring to detect unauthorized data transmission from development environments
• Enable detailed logging of Claude Code operations and context window inputs
• Set up alerts for Claude Code installations running deprecated versions

How to Mitigate CVE-2025-55284

Immediate Actions Required

• Verify that Claude Code is updated to version 1.0.4 or later
• Audit all Claude Code installations across the organization for deprecated versions
• Review recent Claude Code activity logs for any signs of exploitation
• Ensure auto-update functionality is enabled for all Claude Code installations

Patch Information

Anthropic has released version 1.0.4 of Claude Code which addresses this vulnerability. Users on standard Claude Code auto-update received this fix automatically after release. Current users of Claude Code are unaffected, as versions prior to 1.0.24 are deprecated and have been forced to update.

For detailed patch information, consult the GitHub Security Advisory GHSA-x5gv-jw7f-j6xj.

Workarounds

• Enable auto-update for Claude Code to ensure automatic security patch deployment
• Restrict Claude Code's network access using firewall rules until patching is complete
• Exercise caution when opening untrusted projects or pasting content from external sources into Claude Code
• Implement network monitoring to detect potential data exfiltration attempts from development environments

# Verify Claude Code version
claude --version

# Ensure version is 1.0.4 or later
# If running an older version, update immediately:
npm update @anthropic-ai/claude-code