CVE-2023-4138: No rate limit on send report functionality results in an email spam in rdiffweb

Description

There is no rate limit on the send report feature on the https://rdiffweb-dev.ikus-soft.com/prefs/notification endpoint , which allows an attacker to spam the victims mailbox

Proof of Concept

1) Go to https://rdiffweb-dev.ikus-soft.com/prefs/notification 
2) Click on daily frequency for Send me a backup status report 
3) Turn on your intercept and capture the request while you Click the Save and send report button . 
4) Send this report to the repeater and send the same request 100 times .
5) You will see that the mailbox has been spammed

Impact

Due to lack of rate limit this may create an email spam attack or may put immense load on the mail server being used causing additional expenses for the organisation