CVE-2025-69256

HIGH

Serverless Framework 4.29.0-4.29.3 - Remote Code Execution via MCP Server Input Injection

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 3 public exploits for CVE-2025-69256. PoCs published by studiomeyer-io, SimoesCTT.

AI-analyzed exploit summary This repository provides a detailed technical analysis and mitigation tool for shell injection vulnerabilities in Node.js child_process.exec/spawn, including a library wrapper, audit CLI, and sandboxing mechanisms. It addresses CVE-2025-69256 with comprehensive fixes for Unicode bypasses, replay detection, and allowlist validation.

Description

The Serverless Framework is a framework for using AWS Lambda and other managed cloud services to build applications. Starting in version 4.29.0 and prior to version 4.29.3, a command injection vulnerability exists in the Serverless Framework's built-in MCP server package (@serverless/mcp). This vulnerability only affects users of the experimental MCP server feature (serverless mcp), which represents less than 0.1% of Serverless Framework users. The core Serverless Framework CLI and deployment functionality are not affected. The vulnerability is caused by the unsanitized use of input parameters within a call to `child_process.exec`, enabling an attacker to inject arbitrary system commands. Successful exploitation can lead to remote code execution under the server process's privileges. The server constructs and executes shell commands using unvalidated user input directly within command-line strings. This introduces the possibility of shell metacharacter injection (`|`, `>`, `&&`, etc.). Version 4.29.3 fixes the issue.

Exploits (3)

nomisec WRITEUP
by studiomeyer-io · poc
https://github.com/studiomeyer-io/mcp-stdio-shellguard

This repository provides a detailed technical analysis and mitigation tool for shell injection vulnerabilities in Node.js child_process.exec/spawn, including a library wrapper, audit CLI, and sandboxing mechanisms. It addresses CVE-2025-69256 with comprehensive fixes for Unicode bypasses, replay detection, and allowlist validation.

Classification
Writeup 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: Node.js applications using child_process.exec/spawn
No auth needed
Prerequisites: Node.js environment · Access to vulnerable child_process calls
devstral-2 · analyzed May 08, 2026 Full analysis →
nomisec WRITEUP
by studiomeyer-io · poc
https://github.com/studiomeyer-io/mcp-server-attestation

This repository provides a detailed technical analysis and mitigation for CVE-2025-69256, including a library for Ed25519 signing/verification, manifest schema validation, and runtime spawn attestation. It includes CVE-replay fixtures and security measures like argument sanitization and trust file validation.

Classification
Writeup 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: Serverless Framework MCP (specific version not specified)
No auth needed
Prerequisites: Access to the target MCP server · Ability to send crafted requests
devstral-2 · analyzed Apr 28, 2026 Full analysis →
nomisec WORKING POC
by SimoesCTT · poc
https://github.com/SimoesCTT/CTT-Serverless-RCE-v1.0---Convergent-Time-Theory-Enhanced-MCP-Exploit

The repository contains a functional exploit for CVE-2025-69256, targeting the Serverless Framework MCP Server via command injection in the 'workspaceRoots' parameter. The exploit uses a custom 'Convergent Time Theory' (CTT) resonance engine to optimize timing and payload encoding for reliable RCE.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Complex
Reliability
Reliable
Target: Serverless Framework MCP Server
No auth needed
Prerequisites: Network access to the MCP server port (default: 3000) · Vulnerable version of Serverless Framework MCP Server
devstral-2 · analyzed Feb 19, 2026 Full analysis →

Scores

CVSS v3 7.5
EPSS 0.0006
EPSS Percentile 17.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact total

Details

CWE
CWE-77
Status published
Products (3)
npm/serverless 4.29.0 - 4.29.3npm
serverless/serverless 4.29.0 - 4.29.3
serverless/serverless >= 4.29.0, < 4.29.3
Published Dec 30, 2025
Tracked Since Feb 18, 2026