Denial of Service (DoS) Affecting multer package, versions <2.3.0

Affected versions of this package are vulnerable to Denial of Service (DoS) via the diskStorage engine's _handleFile function, which fails to close or destroy the destination write stream when an upload is aborted before it completes. Each aborted request leaks an open file descriptor and retains its disk blocks until the process exits, allowing an attacker to exhaust the process's available file descriptors by repeatedly initiating and aborting multipart file uploads, causing a denial of service.

Note: This is only exploitable when diskStorage is used as the multer storage engine.

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

• GitHub Advisory
• GitHub Commit
• Vendor Advisory