# Download Bypass: Poison Null Byte

If you cannot download files of a certain type, try a character bypass called "Poison Null Byte". A Poison Null Byte looks like this: %00.  The Poison Null Byte will now look like this: %2500. Adding this and then a **.md** to the end will bypass the 403 error!

e.g. \<url>/ftp/package.json.bak%2500.md


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://wiki.zacheller.dev/web-app-pentest/upload-download/error-only-.md-and-.pdf-files-are-allowed.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.