CVE-2026-5528: code-screenshot-mcp RCE Vulnerability

CVE-2026-5528 Overview

A critical OS command injection vulnerability has been identified in MoussaabBadla code-screenshot-mcp versions up to 0.1.0. The vulnerability exists in the HTTP Interface component, where improper input validation allows attackers to inject and execute arbitrary operating system commands. The exploit has been publicly disclosed, and despite early contact attempts, the vendor has not responded to disclosure notifications.

Critical Impact

Remote attackers with low privileges can exploit this command injection flaw to execute arbitrary OS commands on the target system, potentially leading to complete system compromise, data exfiltration, or lateral movement within the network.

Affected Products

• MoussaabBadla code-screenshot-mcp version 0.1.0 and earlier
• Systems exposing the code-screenshot-mcp HTTP Interface to untrusted networks

Discovery Timeline

• 2026-04-05 - CVE-2026-5528 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2026-5528

Vulnerability Analysis

This vulnerability is classified as CWE-77 (Improper Neutralization of Special Elements used in a Command - Command Injection). The flaw resides within the HTTP Interface component of code-screenshot-mcp, a tool designed to generate code screenshots. User-supplied input processed through the HTTP interface is not properly sanitized before being passed to operating system command execution functions, allowing attackers to break out of the intended command context and inject malicious commands.

The attack can be performed remotely over a network connection by any authenticated user with low privileges. No user interaction is required for exploitation, making this vulnerability particularly dangerous in environments where the affected service is exposed to untrusted networks or multi-tenant environments.

Root Cause

The root cause of this vulnerability is insufficient input validation and sanitization in the HTTP Interface component. When processing user requests, the application constructs OS commands using unsanitized input parameters. Special shell metacharacters such as semicolons, pipes, backticks, or command substitution syntax are not properly escaped or filtered, enabling attackers to append or inject additional commands that execute with the privileges of the application process.

Attack Vector

The vulnerability is exploitable over the network (AV:N) with low attack complexity. An attacker can craft malicious HTTP requests to the vulnerable interface containing shell metacharacters and arbitrary commands. When the application processes these requests, the injected commands are executed by the underlying operating system.

Typical exploitation scenarios include:

1. Injecting commands via URL parameters or HTTP request body fields processed by the screenshot generation functionality
2. Using shell metacharacters such as ;, |, &&, ||, or command substitution ($(...) or backticks) to chain malicious commands
3. Exfiltrating sensitive data, establishing reverse shells, or deploying additional malware on compromised systems

The vulnerability has been publicly disclosed via a GitHub Issue Report, increasing the likelihood of exploitation attempts.

Detection Methods for CVE-2026-5528

Indicators of Compromise

• Unusual HTTP requests to code-screenshot-mcp endpoints containing shell metacharacters (;, |, &&, $(, backticks)
• Unexpected child processes spawned by the code-screenshot-mcp application process
• Outbound network connections from the server hosting code-screenshot-mcp to unknown external IP addresses
• Anomalous system commands in application logs or process monitoring tools

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests containing OS command injection patterns
• Monitor application logs for unusual input patterns, especially those containing shell metacharacters
• Deploy endpoint detection and response (EDR) solutions to identify suspicious process chains originating from the web application
• Use intrusion detection systems (IDS) to alert on known command injection attack signatures

Monitoring Recommendations

• Enable verbose logging on the HTTP Interface and review logs for suspicious request patterns
• Configure process monitoring to alert when the code-screenshot-mcp process spawns unexpected child processes
• Implement network segmentation to isolate the vulnerable service and monitor egress traffic for anomalies
• Set up alerting for any outbound connections from the application server to unexpected destinations

How to Mitigate CVE-2026-5528

Immediate Actions Required

• Restrict network access to the code-screenshot-mcp HTTP Interface to trusted IP addresses only
• Disable or remove the affected service if not actively required in production environments
• Implement a reverse proxy or WAF with strict input validation rules in front of the vulnerable endpoint
• Monitor for exploitation attempts while awaiting an official patch from the vendor

Patch Information

At the time of this publication, no official patch has been released by the vendor. The vendor was contacted early about this disclosure but did not respond. Users should monitor the project's official repository for security updates and apply patches immediately when available. Additional technical details are available at the VulDB Vulnerability #355281 entry.

Workarounds

• Deploy the service behind a reverse proxy that implements strict input validation and sanitizes all user input before forwarding requests
• Use application-level firewalls to block requests containing common command injection payloads
• Implement network segmentation to limit the blast radius if the vulnerability is exploited
• Consider replacing the vulnerable component with an alternative tool that does not have known command injection vulnerabilities

# Example: Restrict access using iptables (adjust IP ranges as needed)
# Allow only trusted networks to access the service port
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP