PayU ASN Blocked by CloudFlare - Understanding the Issue

Hello everyone,

I hope you’re doing well.
We recently implemented Cloudflare to enhance our website’s security and performance. However, after the deployment, we encountered an unexpected issue with PayU payment processing. It seems that the entire ASN of PayU was getting a 403 Forbidden error.

To resolve the problem, we had to add the PayU ASN to Cloudflare’s allowlist, and everything started working fine. Nevertheless, this raised some questions: Why did Cloudflare automatically block an entire ASN like PayU? What criteria or rules are used to determine which companies or services get blocked by default?

If anyone has insights into why certain companies or services like PayU might end up on the default blocklist, or if there is a place where we can find a comprehensive list of such blocked services, we would greatly appreciate.


Link to a similar topic but with no concrete answer

No companies or entire ASNs are blocked by default. Depending on your security settings, they may have been being challenged due to IP Reputation, or if you have WAF enabled, failing one of the WAF Rules.
You can find what blocked them exactly under Security → Events (Magic Link:
It could also be Bot Fight Mode, or a custom rule you created. The Security Events tab would say exactly what.

The person’s topic you linked is unrelated, he purposefully blocked an entire ASN and was trying to exclude a specific bot from the block.

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