CVE-2025-53967: Framelink Figma MCP Server RCE Flaw

CVE-2025-53967 Overview

CVE-2025-53967 is a command injection vulnerability affecting Framelink Figma MCP Server versions prior to 0.6.3. The vulnerability allows an unauthenticated remote attacker to execute arbitrary operating system commands via a crafted HTTP POST request containing shell metacharacters. The vulnerable endpoint fails to properly sanitize user-supplied input that is subsequently used by a fetchWithRetry curl command, enabling attackers to inject malicious commands that execute with the privileges of the MCP process.

Critical Impact

Successful exploitation enables unauthenticated remote code execution on systems running vulnerable Framelink Figma MCP Server versions, potentially leading to complete system compromise, data exfiltration, or lateral movement within the network.

Affected Products

• Framelink Figma MCP Server versions prior to 0.6.3
• Systems with network-accessible MCP interfaces
• Figma-Context-MCP deployments using vulnerable fetch-with-retry.ts implementation

Discovery Timeline

• 2025-10-08 - CVE-2025-53967 published to NVD
• 2025-10-08 - Last updated in NVD database

Technical Details for CVE-2025-53967

Vulnerability Analysis

This vulnerability is classified under CWE-420 (Unprotected Alternate Channel) and represents a critical command injection flaw in the Framelink Figma MCP Server. The vulnerable component resides in the fetch-with-retry.ts file, specifically within the fetch function implementation that handles HTTP requests.

The core issue stems from the application's failure to implement proper input sanitization before passing user-controlled data to shell commands. When the MCP server processes HTTP POST requests, attacker-supplied input containing shell metacharacters is passed directly to a curl command executed via the fetchWithRetry function. This allows an attacker to break out of the intended command context and execute arbitrary system commands.

Exploitation requires network access to the MCP interface, typically available on adjacent network segments. No authentication is required to exploit this vulnerability, making it particularly dangerous in environments where the MCP server is exposed to untrusted networks.

Root Cause

The root cause of CVE-2025-53967 lies in improper input validation within the fetchWithRetry function located in the fetch-with-retry.ts module. The function constructs shell commands using unsanitized user input, allowing shell metacharacters such as ;, |, &&, $(), and backticks to be interpreted by the underlying shell. This design flaw enables command injection attacks where malicious payloads embedded in HTTP POST request parameters are executed as operating system commands.

Attack Vector

The attack vector for this vulnerability requires adjacent network access to the MCP server interface. An attacker positioned on the same network segment can craft malicious HTTP POST requests containing shell metacharacters in input fields processed by the vulnerable fetchWithRetry curl command.

The exploitation mechanism involves injecting command separators or command substitution syntax into request parameters. When the MCP server processes these requests, the injected commands are executed with the same privileges as the MCP process, potentially allowing the attacker to:

• Execute arbitrary system commands
• Read or modify sensitive files
• Establish reverse shells for persistent access
• Pivot to other systems on the network
• Exfiltrate sensitive design data and credentials

The vulnerable code path can be examined in the GitHub Fetch Function Implementation. For detailed technical analysis of the exploitation techniques, refer to the Imperva Blog RCE Vulnerability Analysis.

Detection Methods for CVE-2025-53967

Indicators of Compromise

• Unusual HTTP POST requests to the MCP server containing shell metacharacters such as ;, |, &&, $(, or backticks
• Unexpected child processes spawned by the MCP server process
• Anomalous outbound network connections from the MCP server, potentially indicating reverse shell activity
• Suspicious curl command executions with non-standard parameters or redirections

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests containing shell metacharacters in POST parameters
• Monitor MCP server process trees for unexpected child processes or shell invocations
• Deploy network intrusion detection signatures to identify command injection payloads in HTTP traffic
• Enable comprehensive logging on the MCP server and analyze for malformed or suspicious requests

Monitoring Recommendations

• Configure real-time alerting for any curl command executions spawned from the MCP process context
• Establish baseline behavior for the MCP server and alert on deviations in process activity or network connections
• Implement file integrity monitoring on critical system files that could be targeted post-exploitation
• Monitor for signs of data exfiltration or unauthorized access to Figma design assets

How to Mitigate CVE-2025-53967

Immediate Actions Required

• Upgrade Framelink Figma MCP Server to version 0.6.3 or later immediately
• Restrict network access to the MCP interface using firewall rules to limit exposure to trusted networks only
• Review MCP server logs for any signs of exploitation attempts prior to patching
• Consider temporarily disabling the MCP server if immediate patching is not possible

Patch Information

The vulnerability has been addressed in Framelink Figma MCP Server version 0.6.3. The security fix implements proper input sanitization to prevent shell metacharacter injection in the fetchWithRetry function. Organizations should upgrade to the patched version available at GitHub Release Version 0.6.3.

Workarounds

• Implement network segmentation to isolate the MCP server from untrusted network segments
• Deploy a reverse proxy with input validation capabilities in front of the MCP server to filter malicious requests
• Use application-level firewalls to block requests containing common shell metacharacters
• Restrict the MCP server process privileges using operating system security mechanisms such as AppArmor or SELinux

# Example: Restrict MCP server network access using iptables
# Allow only trusted IP ranges to access the MCP interface
iptables -A INPUT -p tcp --dport 3000 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 3000 -j DROP