CVE-2026-7216: Claude MCP Bridge Path Traversal Flaw

CVE-2026-7216 Overview

A path traversal vulnerability has been identified in donchelo processing-claude-mcp-bridge, affecting versions up to commit e017b20a4b592a45531a6392f494007f04e661bd. The vulnerability exists in the processing_server.py file within the create_sketch tool functionality. By manipulating the sketch_name argument, an attacker can perform path traversal attacks to access files or directories outside the intended scope.

Critical Impact
Remote attackers can exploit this path traversal vulnerability to read, write, or manipulate files outside the designated directory structure, potentially leading to information disclosure, data corruption, or further system compromise.

Affected Products

donchelo processing-claude-mcp-bridge (rolling release up to commit e017b20a4b592a45531a6392f494007f04e661bd)

Discovery Timeline

2026-04-28 - CVE CVE-2026-7216 published to NVD
2026-04-29 - Last updated in NVD database

Technical Details for CVE-2026-7216

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), commonly known as path traversal. The flaw resides in the create_sketch tool within processing_server.py, where the sketch_name parameter is not properly sanitized before being used in file system operations.

When users provide a crafted sketch_name value containing directory traversal sequences (such as ../), the application fails to restrict the resulting path to the intended directory. This allows attackers to escape the expected file system boundaries and access arbitrary locations on the server.

The project operates on a rolling release model, meaning there are no versioned releases to reference. The vulnerability is exploitable remotely over the network without requiring authentication, making it accessible to unauthenticated attackers. An exploit has been made publicly available, increasing the risk of active exploitation in the wild.

Root Cause

The root cause of this vulnerability is insufficient input validation and path sanitization in the create_sketch tool. The sketch_name argument is directly incorporated into file path construction without proper filtering of path traversal characters or validation against a whitelist of acceptable patterns. The application does not canonicalize the path or verify that the resolved path remains within the intended base directory.

Attack Vector

This vulnerability can be exploited remotely over the network. An attacker can send malicious requests to the processing-claude-mcp-bridge service with a crafted sketch_name parameter containing directory traversal sequences. No authentication or user interaction is required for exploitation.

The attack leverages the create_sketch tool by injecting path traversal sequences like ../ into the sketch_name parameter. When the application processes this input without sanitization, it constructs a file path that escapes the intended sketch directory, allowing the attacker to read or write files in arbitrary locations accessible to the application's running user context.

For detailed technical information, see the GitHub Issue Tracker and VulDB entry #359816.

Detection Methods for CVE-2026-7216

Indicators of Compromise

Unusual file access patterns in application logs showing path traversal sequences (../, ..\)
Unexpected file read or write operations outside the designated sketch directory
HTTP requests to the processing-claude-mcp-bridge service containing encoded directory traversal characters in the sketch_name parameter
Modified or new files appearing in unexpected system directories

Detection Strategies

Implement web application firewall (WAF) rules to detect and block requests containing path traversal patterns in API parameters
Monitor application logs for sketch_name parameters containing suspicious characters or patterns
Deploy file integrity monitoring (FIM) on sensitive directories to detect unauthorized access or modifications
Use intrusion detection systems (IDS) with signatures for common path traversal attack patterns

Monitoring Recommendations

Enable verbose logging on the processing-claude-mcp-bridge service to capture all incoming requests with full parameter details
Set up alerts for file system operations that attempt to access paths outside the designated application directories
Monitor network traffic for unusual request patterns targeting the create_sketch endpoint

How to Mitigate CVE-2026-7216

Immediate Actions Required

Restrict network access to the processing-claude-mcp-bridge service to trusted IP addresses only
Implement input validation at the network edge using a reverse proxy or WAF to block path traversal patterns
Consider disabling the create_sketch functionality until a patch is available
Review application logs for signs of prior exploitation attempts

Patch Information

No official patch has been released at the time of publication. The project maintainer was notified through an issue report but has not responded. Users should monitor the project repository for updates and apply any security fixes as soon as they become available. Given the rolling release nature of this project, users should pull the latest commits once a fix is confirmed.

Workarounds

Deploy a reverse proxy or WAF in front of the service configured to reject requests containing path traversal sequences in the sketch_name parameter
Implement filesystem sandboxing or chroot jails to limit the directories accessible to the application
Run the service with minimal filesystem permissions using a dedicated low-privilege user account
Use network segmentation to isolate the affected service from sensitive systems and data

bash

# Example: Input validation pattern for sketch_name (implement in application code)
# Reject any sketch_name containing path separators or traversal sequences
# Valid pattern: alphanumeric characters, underscores, and hyphens only
# Pattern: ^[a-zA-Z0-9_-]+$