Denial of Service (DoS) Affecting starlette package, versions [,0.25.0)

starlette is a The little ASGI library that shines.

Affected versions of this package are vulnerable to Denial of Service (DoS) via the MultipartParser class, which accepts an unlimited number of fields and files when parsing multipart/form-data. Exploiting this vulnerability is possible by sending too many small form fields with no content or too many empty files, which results in high CPU usage and high memory usage.

Note:

An affected application has to have all the following:

1. python-multipart installed.

2. calls request.form().

Applications that don't install python-multipart or that don't use form fields are safe.

In older versions, it's also possible to instead of calling request.form() call request.stream() and parse the form data in internal code.

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

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