CVE-2026-50757: next-ai-draw-io Path Traversal Flaw

CVE-2026-50757 Overview

CVE-2026-50757 is a directory traversal vulnerability affecting DayuanJiang next-ai-draw-io version 0.4.13. The flaw resides in the nex-ai-draw-io/mcp-server component and is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory. A remote attacker can leverage insufficient path validation to traverse outside the intended directory and execute arbitrary code on the host running the Model Context Protocol (MCP) server. Exploitation requires user interaction, and the attack vector is local to the process handling untrusted input. The vulnerability impacts confidentiality, integrity, and availability of the affected system.

Critical Impact
Successful exploitation allows an attacker to write or access files outside the intended directory scope and achieve arbitrary code execution on the host running next-ai-draw-io 0.4.13.

Affected Products

DayuanJiang next-ai-draw-io version 0.4.13
nex-ai-draw-io/mcp-server component
Downstream applications integrating the vulnerable MCP server

Discovery Timeline

2026-07-21 - CVE-2026-50757 published to NVD
2026-07-22 - Last updated in NVD database

Technical Details for CVE-2026-50757

Vulnerability Analysis

The vulnerability exists in the MCP server component of next-ai-draw-io, an AI-assisted diagramming tool. The server accepts file path parameters without properly canonicalizing or validating them against an allowlisted base directory. An attacker who can supply crafted path input, for example through prompts consumed by the MCP server or through file operations exposed to a client, can include traversal sequences such as ../ to escape the intended working directory. Because the MCP server executes with the privileges of the invoking user, escaping the sandboxed directory allows read, write, or overwrite of arbitrary files. Writing to executable locations or configuration files leads to arbitrary code execution.

Root Cause

The root cause is improper limitation of a pathname to a restricted directory [CWE-22]. The nex-ai-draw-io/mcp-server handler concatenates user-influenced path segments with a base directory without rejecting .. sequences, absolute paths, or symbolic link redirections. No canonicalization step compares the resolved path against the intended parent directory before file operations occur.

Attack Vector

Exploitation requires the victim to interact with attacker-controlled content processed by the MCP server. This aligns with the user interaction requirement in the CVSS vector. Typical scenarios include a user loading a malicious diagram, prompt, or workspace file that instructs the MCP server to read or write paths containing traversal sequences. The attacker delivers the payload through channels such as shared diagram files, malicious repositories, or crafted MCP tool invocations. Once the traversal succeeds, the attacker plants or modifies files that execute in the user's context, achieving code execution.

Refer to the GitHub CVE-2026-50757 details and GitHub Issue Discussion #754 for reproduction context.

Detection Methods for CVE-2026-50757

Indicators of Compromise

File operations originating from the nex-ai-draw-io/mcp-server process that reference paths containing .., URL-encoded traversal sequences such as %2e%2e%2f, or absolute paths outside the configured workspace.
Unexpected writes by the MCP server process to user startup locations, shell configuration files, or application autoload directories.
MCP tool invocations containing path parameters that resolve outside the intended project directory.

Detection Strategies

Enable filesystem auditing on hosts running next-ai-draw-io 0.4.13 and alert on writes by the MCP server to paths outside its designated workspace directory.
Inspect MCP server logs for tool calls whose arguments contain traversal metacharacters or absolute path prefixes.
Correlate diagram or workspace file ingestion events with subsequent file writes or process launches by the same parent process.

Monitoring Recommendations

Monitor child process creation from the Node.js runtime hosting the MCP server and flag execution of interpreters or shells that were not previously observed.
Track modifications to user profile scripts, scheduled tasks, and application plugin directories on developer workstations running the tool.
Aggregate MCP request telemetry to a central log store to enable retroactive hunting once patched signatures are known.

How to Mitigate CVE-2026-50757

Immediate Actions Required

Stop running next-ai-draw-io version 0.4.13 with untrusted diagrams, workspaces, or MCP tool inputs until a fixed release is available.
Restrict the MCP server to a dedicated low-privilege user account and a filesystem sandbox that has no access to sensitive files.
Review the GitHub Issue Discussion #754 for maintainer updates and apply any published fix immediately.

Patch Information

At the time of NVD publication on 2026-07-21, no vendor patch reference is listed in the CVE record. Track the upstream repository issue tracker for a fixed release above version 0.4.13 and upgrade as soon as a patched version is published.

Workarounds

Run the MCP server inside a container or chroot with a read-only bind mount limited to the required workspace directory.
Configure the operating system to deny writes by the MCP server user to shell startup files, scheduled task directories, and application autoload paths.
Reject or sanitize MCP tool inputs at a proxy layer, dropping requests whose path arguments contain .., null bytes, or absolute paths.

bash

# Example: run the MCP server as an unprivileged user inside a restricted directory
useradd -r -m -d /var/lib/mcp-nai -s /usr/sbin/nologin mcp-nai
install -d -o mcp-nai -g mcp-nai -m 0750 /var/lib/mcp-nai/workspace
sudo -u mcp-nai firejail \
  --private=/var/lib/mcp-nai \
  --whitelist=/var/lib/mcp-nai/workspace \
  --read-only=/var/lib/mcp-nai \
  --read-write=/var/lib/mcp-nai/workspace \
  node ./nex-ai-draw-io/mcp-server