lack of input validation that can lead Denial of Service (DOS)

How it was found

Hi Security Team,

Summary:

There is no limit to the number of characters in the issue comments, which allows a DoS attack. The DoS attack affects server-side.

Description

On the input form of Username in https://twitter.com/settings/screen_name there's no Input validation using this you can send more payload and may cause of Denial of service or error code 500 Internal Server Error/Internal Error

Proof of Concept

1. First login your twitter account
2. Go to the Settings of your account
3. Click Username
4. Change your username and put the payload then submit

And the response was pop up and say. ==Something went wrong, but don't fret --- it's not your fault.== and the response code on the server side is 500 Internal Server Error

Kindly check 2 uploaded photo for my additional Proof of Concept

Remediation:

Implementing input validation
Validating free-form Unicode text
Define the allowed set of characters to be accepted.
Minimum and maximum value range

Supporting Material/References:

payload.txt

Thank you! Regards

Impact

Attacker can perform a DOS because of lack of input validation