check_resource_allowed treats /api/../admin as under /api

What happened

check_resource_allowed pads trailing slashes and then does requested_path.startswith(configured_path). It does not collapse . / ...

On main @ 08a3bc8 these return True:

• requested https://example.com/api/../admin vs configured https://example.com/api
• requested https://example.com/mcp/.. vs configured https://example.com/mcp
• requested https://example.com/api/%2e%2e/admin vs configured https://example.com/api

tests/shared/test_auth_utils.py already rejects /api123 vs /api (path-boundary). Dot-segments are not covered.

What I expected

A requested path that walks out of the configured prefix should not match. /api/foo/../v1 vs /api can still match after normalisation, because it stays under /api.

How to reproduce

from mcp.shared.auth_utils import check_resource_allowed

check_resource_allowed("https://example.com/api/../admin", "https://example.com/api")
# True today. I expected False.

I can send a PR that percent-decodes once, runs posixpath.normpath, then keeps the existing trailing-slash prefix rule. Happy to do that if you want it.

Written with AI assistance. I read auth_utils.py next to the path-boundary tests and reproduced it locally.

Commencez dans auth_utils.py, au niveau de check_resource_allowed, et examinez les cas existants de limites de chemin dans tests/shared/test_auth_utils.py. Ajoutez une couverture pour les segments de point, les segments de point encodés en pourcentage et les chemins qui restent sous le préfixe configuré, puis exécutez les tests pertinents des utilitaires auth. C’est terminé lorsque les chemins qui sortent du préfixe configuré ne correspondent pas, tandis que les chemins normalisés qui restent sous celui-ci correspondent toujours.