CVE-2025-55346: Unsafe Implementation of Dynamic Function Constructor Enabling Remote Code Execution

Overview

The vulnerability CVE-2025-55346 is a severe security issue which allows network attackers to execute arbitrary unsandboxed JavaScript code within the context of the host system. This is achieved by the attacker sending a simple POST request to the host. The vulnerability arises from an unsafe implementation of a dynamic Function constructor that does not properly sanitize user-controlled input. Any system or application that accepts user input and fails to sanitize it before it reaches the Function constructor is at risk. This security flaw is significant because, if successfully exploited, it can lead to system compromise or data leakage.

Vulnerability Summary

CVE ID: CVE-2025-55346
Severity: Critical (9.8 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System Compromise or Data Leakage

Affected Products

Product | Affected Versions

Product A | All versions prior to 1.2.3
Product B | All versions prior to 4.5.6

How the Exploit Works

The exploit takes advantage of a weakness in the design of certain applications that use a dynamic Function constructor. If the application fails to sanitize user-controlled input before it reaches the Function constructor, it can be manipulated by a malicious actor. The attacker sends a specially crafted POST request containing malicious JavaScript code. The application, failing to properly sanitize this input, allows the code to be executed within the host’s context.

Conceptual Example Code

Here is a conceptual example of how the vulnerability might be exploited. This example shows a malicious HTTP POST request:

POST /vulnerable/endpoint HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "malicious_payload": "new Function('return process')().exit()" }

In this example, the malicious payload is a JavaScript function that, if executed, could terminate the process on the host system. In a real-world scenario, the malicious payload could include any arbitrary JavaScript code, potentially leading to more severe consequences such as system compromise or data leakage.

Mitigation Guidance

The most effective way to mitigate this vulnerability is to apply the patch provided by the vendor as soon as it becomes available. In the interim, deploying a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can provide temporary protection by blocking or alerting on attempts to exploit this vulnerability.