CVE-2025-69256 in serverless
Summary
by MITRE • 12/30/2025
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.
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Analysis
by VulDB Data Team • 03/23/2026
The Serverless Framework represents a widely adopted infrastructure-as-code solution that enables developers to build applications using AWS Lambda and other managed cloud services. This framework has gained significant traction in enterprise environments where serverless computing architectures are prevalent. The vulnerability identified in CVE-2025-69256 specifically targets the experimental MCP server feature within the @serverless/mcp package, which operates as a built-in server component for managing serverless configurations. The affected versions span from 4.29.0 through 4.29.2, creating a narrow window of exposure for organizations utilizing this experimental functionality. This vulnerability operates at the intersection of software security and cloud infrastructure management, where the attack surface extends beyond traditional application boundaries into system-level command execution capabilities.
The technical flaw manifests through improper input validation within the MCP server implementation where user-provided parameters are directly incorporated into shell command execution without adequate sanitization. This vulnerability directly maps to CWE-78, which describes improper neutralization of special elements used in OS commands, commonly known as OS command injection. The implementation utilizes the child_process.exec function in Node.js without proper parameter sanitization, creating an environment where malicious actors can inject arbitrary shell commands through carefully crafted input parameters. The vulnerability's exploitation pathway involves constructing shell command strings that include unvalidated user input, enabling attackers to leverage shell metacharacters such as pipe operators, redirection symbols, and logical operators to execute unauthorized system commands. This represents a classic command injection vulnerability that bypasses traditional application-level security controls by operating at the system call level.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise under the privileges of the server process. When exploited, attackers can gain unauthorized access to the underlying infrastructure, potentially leading to data exfiltration, system modification, or further lateral movement within the cloud environment. The low user adoption rate of the experimental MCP server feature, estimated at less than 0.1% of total Serverless Framework users, limits the overall exposure but does not eliminate the severity of potential impact for affected organizations. The vulnerability affects only the specific mcp command functionality and does not compromise the core Serverless Framework CLI or deployment mechanisms, providing a clear attack surface boundary. Organizations utilizing the experimental MCP feature face a critical security risk that could lead to unauthorized system access and potential cloud resource compromise.
Mitigation strategies should focus on immediate version upgrading to 4.29.3 or later, which contains the necessary patches addressing the command injection vulnerability. Security teams should implement monitoring for unusual command execution patterns and shell activity within environments where the MCP server feature is enabled. Organizations should conduct comprehensive risk assessments to identify all systems utilizing the experimental MCP functionality and ensure complete remediation. The vulnerability demonstrates the importance of input validation and proper sanitization of user-provided data before system command execution, aligning with ATT&CK technique T1059.001 for command and scripting interpreter. Additionally, implementing principle of least privilege for server processes and network segmentation can help limit potential damage from successful exploitation attempts. Regular security assessments and dependency updates remain critical practices for maintaining secure serverless infrastructure deployments.