Overview
The vulnerability CVE-2025-47935 pertains to Multer, a node.js middleware for handling multipart/form-data. This vulnerability potentially affects all users of Multer that process file uploads. The issue arises from poor stream handling, leading to a resource exhaustion and memory leak, which could result in a denial of service and necessitate manual server restarts. This is a significant threat as it could result in potential system compromise or data leakage.
Vulnerability Summary
CVE ID: CVE-2025-47935
Severity: High (7.5)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Denial of Service, Potential System Compromise, Data Leakage
Affected Products
Product | Affected Versions
Multer | Less than 2.0.0
How the Exploit Works
The exploit takes advantage of a flaw in Multer versions prior to 2.0.0. When the HTTP request stream emits an error, the internal ‘busboy’ stream is not properly closed. This violates Node.js’ stream safety guidance. Over time, the accumulation of these unclosed streams leads to memory and file descriptor consumption, causing a resource exhaustion and memory leak. Under sustained or repeated failure conditions, this can result in a denial of service attack.
Conceptual Example Code
This conceptual example demonstrates a simple request that could trigger the vulnerability:
POST /upload HTTP/1.1
Host: target.example.com
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW
------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="file"; filename="malicious_file.txt"
Content-Type: text/plain
[Malicious content]
------WebKitFormBoundary7MA4YWxkTrZu0gW--After this request, an error is emitted, leading to an unclosed stream, which if repeated could lead to a denial of service.
