---
title: How Blacklists, Whitelists, and Graylists Are Processed
slug: ps/help/en_us/vwaf/ag/how-blacklists-whitelists-and-graylists-are-processed
docTags: 
createdAt: 2026-08-02T10:05:40.032Z
---

When creating or modifying a ruleset, you’ll find various attributes that allow you to specify a blacklist, a whitelist, or a graylist. In order to achieve the desired behavior, you need to understand how vWAFprocesses these lists.

## If there’s only a blacklist

If there’s only a blacklist but no whitelist and no graylist, a vWAF function only looks at the blacklist. If the value that’s to be checked matches a pattern on the blacklist, the function returns FALSE, else it returns TRUE.

## If there’s only a whitelist

If there’s only a whitelist but no blacklist and no graylist, a vWAF function only looks at the whitelist. If the value that’s to be checked matches a pattern on the whitelist, the function returns TRUE, else it returns FALSE.

## If there’s a blacklist, a whitelist, and a graylist

- First, vWAF looks at the blacklist. If the value that’s to be checked matches a pattern on the blacklist, the function returns FALSE and exits. In this case, vWAF doesn’t take any further look at the graylist and at the whiltelist.
- If there has been no match with the blacklist, vWAF next looks at the whitelist. If the value that’s to be checked matches a pattern on the whitelist, the function returns TRUE and exits. In this case vWAF doesn’t take any further look at the graylist..
- If there has been no match with the blacklist and no match with the whitelist, vWAF next also looks at the graylist. If the value that’s to be checked matches a pattern on the graylist, the function returns FALSE, else it returns TRUE.

:::hint{type="info"}
It then depends on the specific handler or selector, how it interprets the function’s result “TRUE” or “FALSE.” See [Handlers](docId\:XeQnKiGViEhlar6KhoTVF) and [Preconditions (Selectors)](docId:4K-Q6R52t9m_t5LuXamCA).
:::