CVE-2026-3680 Overview
A command injection vulnerability has been discovered in RyuzakiShinji biome-mcp-server versions up to 1.0.0. This security flaw exists within the biome-mcp-server.ts file and allows remote attackers to execute arbitrary commands through improper handling of user-supplied input. The exploit has been publicly disclosed, increasing the risk of active exploitation in the wild.
Critical Impact
Remote attackers with low privileges can exploit this command injection flaw to execute arbitrary system commands on affected biome-mcp-server installations, potentially leading to complete system compromise.
Affected Products
- RyuzakiShinji biome-mcp-server versions up to and including 1.0.0
- Any systems running unpatched instances of biome-mcp-server
Discovery Timeline
- 2026-03-07 - CVE-2026-3680 published to NVD
- 2026-03-09 - Last updated in NVD database
Technical Details for CVE-2026-3680
Vulnerability Analysis
This vulnerability is classified under CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), commonly referred to as injection. The flaw exists in the biome-mcp-server.ts file where user-controlled input is passed to system command execution functions without proper sanitization or validation.
Command injection vulnerabilities of this nature allow attackers to break out of the intended command context and execute arbitrary system commands. In the context of an MCP (Model Context Protocol) server, this is particularly dangerous as these servers often have elevated privileges to perform various system operations.
The vulnerability can be exploited remotely over the network with low attack complexity and requires only low-level privileges to execute successfully. The impact affects confidentiality, integrity, and availability of the target system, though each impact category is rated as low individually.
Root Cause
The root cause of CVE-2026-3680 is insufficient input validation and sanitization in the biome-mcp-server.ts file. When processing requests, the application fails to properly neutralize special characters and shell metacharacters before passing user-supplied data to command execution functions. This allows attackers to inject additional commands that the server will execute with its own privileges.
Attack Vector
The attack can be initiated remotely over the network. An authenticated attacker with low privileges can craft malicious input containing shell metacharacters (such as ;, |, &, or backticks) to inject arbitrary commands. The manipulated input is then passed to the vulnerable function in biome-mcp-server.ts, where it is executed by the underlying system shell.
The vulnerability manifests in the command handling functionality within biome-mcp-server.ts. Attackers can exploit this by crafting malicious input that escapes the intended command context and injects arbitrary shell commands. For detailed technical information about the exploitation mechanism, refer to the GitHub Security Advisory PDF and VulDB entry #349582.
Detection Methods for CVE-2026-3680
Indicators of Compromise
- Unusual process spawning from the biome-mcp-server process, particularly shell processes (sh, bash, cmd.exe)
- Unexpected network connections originating from the MCP server process
- Anomalous command-line arguments containing shell metacharacters in server logs
- Suspicious file system modifications in directories accessible by the server process
Detection Strategies
- Monitor process trees for unexpected child processes spawned by biome-mcp-server
- Implement log analysis rules to detect command injection patterns (;, |, &&, ||, backticks, $()) in request parameters
- Deploy application-layer firewalls or WAF rules to filter malicious input patterns targeting command injection
- Review server access logs for requests with unusually long or encoded parameters
Monitoring Recommendations
- Enable verbose logging on biome-mcp-server instances to capture all incoming requests
- Configure SIEM alerts for detection of shell command execution patterns from web server processes
- Implement file integrity monitoring on critical system directories
- Monitor network traffic for unusual outbound connections from server processes
How to Mitigate CVE-2026-3680
Immediate Actions Required
- Update biome-mcp-server to a patched version containing commit 335e1727147efeef011f1ff8b05dd751d8a660be
- Review server logs for evidence of exploitation attempts
- Consider temporarily disabling or restricting access to affected biome-mcp-server instances until patching is complete
- Implement network segmentation to limit the potential impact of exploitation
Patch Information
A patch has been released to address this vulnerability. The fix is identified by commit hash 335e1727147efeef011f1ff8b05dd751d8a660be. Organizations should apply this patch immediately by updating their biome-mcp-server installation.
The patch details can be reviewed at:
Workarounds
- Implement strict input validation at the network perimeter to block requests containing shell metacharacters
- Deploy a reverse proxy with request filtering capabilities in front of vulnerable instances
- Restrict network access to the MCP server to trusted IP addresses only
- Run the biome-mcp-server process with minimal system privileges to limit the impact of successful exploitation
# Update biome-mcp-server to the patched version
cd /path/to/biome-mcp-server
git pull origin main
# Verify the patch is applied
git log --oneline | grep 335e172
# Restart the service
npm run restart
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
