pallets
docs: add warning and best practices for url_for(..., _external=True)…
Description of the Change
This pull request adds a warning and best practices to the Web Security documentation regarding the use of url_for(..., _external=True) without setting SERVER_NAME or trusted_hosts. The new section explains the risk of host header injection and provides recommendations for safer configuration. This aims to improve developer awareness and help prevent potential security vulnerabilities, as discussed in #5718.
How it Addresses the Issue
- Documents the risk of host header injection when generating external URLs.
- Recommends setting SERVER_NAME and using trusted_hosts.
- References the ProxyFix documentation for further guidance.
Relevant Issue fixes #5718
Thanks for working on this! I really appreciate how clearly the risks and recommendations were described.
This patch aligns well with the concerns I originally raised in issue #5718, glad to see it resolved!
Heads up, all this information is wrong in various ways. Do not use AI, especially in regards to information about security.
