CVE-2026-5973: MetaGPT RCE Vulnerability via Command Injection

CVE-2026-5973 Overview

A vulnerability has been identified in FoundationAgents MetaGPT up to version 0.8.1 that allows OS command injection through the get_mime_type function located in metagpt/utils/common.py. This security flaw enables remote attackers to inject and execute arbitrary operating system commands on the target system. The vulnerability has been publicly disclosed, and exploit information is available, though the project maintainers have not yet responded to the issue despite being notified through a pull request.

Critical Impact

Remote attackers can exploit this command injection vulnerability to execute arbitrary OS commands on systems running vulnerable versions of MetaGPT, potentially leading to complete system compromise, data exfiltration, or lateral movement within affected environments.

Affected Products

• FoundationAgents MetaGPT versions up to and including 0.8.1
• Systems utilizing the get_mime_type function in metagpt/utils/common.py

Discovery Timeline

• April 9, 2026 - CVE-2026-5973 published to NVD
• April 9, 2026 - Last updated in NVD database

Technical Details for CVE-2026-5973

Vulnerability Analysis

This vulnerability is classified as CWE-77 (Improper Neutralization of Special Elements used in a Command), commonly known as OS command injection. The flaw exists in the get_mime_type function within the metagpt/utils/common.py file. When processing input to determine file MIME types, the function fails to properly sanitize or validate user-controlled input before passing it to system shell commands.

The vulnerability is network-accessible, meaning attackers can exploit it remotely without requiring any authentication or user interaction. The attack complexity is low, making it relatively straightforward for attackers to leverage this weakness. Upon successful exploitation, attackers gain the ability to execute arbitrary commands with the same privileges as the MetaGPT application process.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and sanitization within the get_mime_type function. When the function processes file paths or filenames to determine their MIME type, it appears to construct and execute shell commands without properly escaping or validating the input. This allows an attacker to inject shell metacharacters or command separators that break out of the intended command context and execute arbitrary commands.

This is a common pattern in applications that rely on external system utilities for file type detection, where developers may use functions like subprocess.call() with shell=True or construct command strings through concatenation rather than using proper parameterization.

Attack Vector

The attack can be executed remotely over the network. An attacker would craft malicious input containing shell metacharacters or command injection payloads and submit it to a component that processes files using the vulnerable get_mime_type function. The injected commands would then be executed on the underlying operating system.

Common injection techniques might include using command separators such as ;, &&, ||, or | to chain additional commands, or using command substitution syntax like $(command) or backticks to embed arbitrary command execution within the original command context.

The vulnerability has been publicly documented through GitHub Issue #1930, and a proposed fix has been submitted via Pull Request #1983. However, as of the disclosure date, the project maintainers have not responded to or merged the fix.

Detection Methods for CVE-2026-5973

Indicators of Compromise

• Unexpected process spawning from MetaGPT application processes, particularly shell interpreters (/bin/sh, /bin/bash, cmd.exe)
• Unusual outbound network connections originating from the MetaGPT process
• Suspicious entries in application logs showing malformed or unusual file path inputs containing shell metacharacters
• Presence of command injection patterns in web server or application access logs (e.g., semicolons, pipes, or command substitution syntax in file-related parameters)

Detection Strategies

• Implement application-level logging to capture all inputs processed by the get_mime_type function and monitor for suspicious patterns
• Deploy network intrusion detection rules to identify potential command injection payloads in traffic destined for MetaGPT instances
• Utilize endpoint detection and response (EDR) solutions to monitor for anomalous child process creation from the MetaGPT application
• Configure SIEM rules to correlate suspicious file path inputs with subsequent unexpected system command execution

Monitoring Recommendations

• Enable verbose logging for the MetaGPT application and monitor the metagpt/utils/common.py module specifically
• Establish baseline behavior for legitimate MetaGPT operations and alert on deviations, particularly unexpected shell command execution
• Monitor system call activity for the MetaGPT process, watching for execve or similar calls that spawn unexpected binaries
• Review and audit all user inputs that flow through file processing pipelines within the application

How to Mitigate CVE-2026-5973

Immediate Actions Required

• Audit all deployments using FoundationAgents MetaGPT version 0.8.1 or earlier and assess exposure
• Implement network segmentation to restrict access to MetaGPT instances from untrusted networks
• Apply input validation at the application perimeter to filter or reject requests containing shell metacharacters in file-related parameters
• Consider disabling or replacing functionality that relies on the vulnerable get_mime_type function until an official patch is available

Patch Information

As of the last update, no official patch has been released by the FoundationAgents MetaGPT project. A community-submitted fix is available via Pull Request #1983, though it has not been officially merged. Organizations should monitor the MetaGPT GitHub repository for updates and apply patches as soon as they become available.

For additional vulnerability tracking information, refer to VulDB #356527.

Workarounds

• Implement a wrapper function around get_mime_type that sanitizes inputs by removing or escaping shell metacharacters before processing
• Replace the vulnerable function with a pure Python MIME type detection library such as python-magic or mimetypes that does not rely on shell command execution
• Deploy a web application firewall (WAF) with rules to detect and block command injection attempts in request parameters
• Run the MetaGPT application in a sandboxed environment or container with restricted system call capabilities using seccomp or AppArmor profiles

# Example: Restricting MetaGPT process capabilities using Docker
# Run with restricted capabilities and read-only filesystem where possible
docker run --cap-drop=ALL --cap-add=NET_BIND_SERVICE \
  --security-opt=no-new-privileges:true \
  --read-only \
  metagpt:0.8.1