Merge pull request from GHSA-g4mx-q9vg-27p4

dummyserver/handlers.py

@@ -281,6 +281,12 @@ def encodingrequest(self, request: httputil.HTTPServerRequest) -> Response:
     def headers(self, request: httputil.HTTPServerRequest) -> Response:
         return Response(json.dumps(dict(request.headers)))
 
+    def headers_and_params(self, request: httputil.HTTPServerRequest) -> Response:
+        params = request_params(request)
+        return Response(
+            json.dumps({"headers": dict(request.headers), "params": params})
+        )
+
     def multi_headers(self, request: httputil.HTTPServerRequest) -> Response:
         return Response(json.dumps({"headers": list(request.headers.get_all())}))
 

src/urllib3/_collections.py

@@ -8,7 +8,7 @@
 if typing.TYPE_CHECKING:
     # We can only import Protocol if TYPE_CHECKING because it's a development
     # dependency, and is not available at runtime.
-    from typing_extensions import Protocol
+    from typing_extensions import Protocol, Self
 
     class HasGettableStringKeys(Protocol):
         def keys(self) -> typing.Iterator[str]:
@@ -391,6 +391,24 @@ def getlist(
             # meets our external interface requirement of `Union[List[str], _DT]`.
             return vals[1:]
 
+    def _prepare_for_method_change(self) -> Self:
+        """
+        Remove content-specific header fields before changing the request
+        method to GET or HEAD according to RFC 9110, Section 15.4.
+        """
+        content_specific_headers = [
+            "Content-Encoding",
+            "Content-Language",
+            "Content-Location",
+            "Content-Type",
+            "Content-Length",
+            "Digest",
+            "Last-Modified",
+        ]
+        for header in content_specific_headers:
+            self.discard(header)
+        return self
+
     # Backwards compatibility for httplib
     getheaders = getlist
     getallmatchingheaders = getlist

src/urllib3/connectionpool.py

@@ -11,6 +11,7 @@
 from types import TracebackType
 
 from ._base_connection import _TYPE_BODY
+from ._collections import HTTPHeaderDict
 from ._request_methods import RequestMethods
 from .connection import (
     BaseSSLError,
@@ -893,7 +894,11 @@ def urlopen(  # type: ignore[override]
         redirect_location = redirect and response.get_redirect_location()
         if redirect_location:
             if response.status == 303:
+                # Change the method according to RFC 9110, Section 15.4.4.
                 method = "GET"
+                # And lose the body not to transfer anything sensitive.
+                body = None
+                headers = HTTPHeaderDict(headers)._prepare_for_method_change()
 
             try:
                 retries = retries.increment(method, url, response=response, _pool=self)

src/urllib3/poolmanager.py

@@ -7,7 +7,7 @@
 from types import TracebackType
 from urllib.parse import urljoin
 
-from ._collections import RecentlyUsedContainer
+from ._collections import HTTPHeaderDict, RecentlyUsedContainer
 from ._request_methods import RequestMethods
 from .connection import ProxyConfig
 from .connectionpool import HTTPConnectionPool, HTTPSConnectionPool, port_by_scheme
@@ -449,9 +449,12 @@ def urlopen(  # type: ignore[override]
         # Support relative URLs for redirecting.
         redirect_location = urljoin(url, redirect_location)
 
-        # RFC 7231, Section 6.4.4
         if response.status == 303:
+            # Change the method according to RFC 9110, Section 15.4.4.
             method = "GET"
+            # And lose the body not to transfer anything sensitive.
+            kw["body"] = None
+            kw["headers"] = HTTPHeaderDict(kw["headers"])._prepare_for_method_change()
 
         retries = kw.get("retries")
         if not isinstance(retries, Retry):

test/with_dummyserver/test_connectionpool.py

@@ -480,6 +480,17 @@ def test_redirect(self) -> None:
             assert r.status == 200
             assert r.data == b"Dummy server!"
 
+    def test_303_redirect_makes_request_lose_body(self) -> None:
+        with HTTPConnectionPool(self.host, self.port) as pool:
+            response = pool.request(
+                "POST",
+                "/redirect",
+                fields={"target": "/headers_and_params", "status": "303 See Other"},
+            )
+        data = response.json()
+        assert data["params"] == {}
+        assert "Content-Type" not in HTTPHeaderDict(data["headers"])
+
     def test_bad_connect(self) -> None:
         with HTTPConnectionPool("badhost.invalid", self.port) as pool:
             with pytest.raises(MaxRetryError) as e:

test/with_dummyserver/test_poolmanager.py

@@ -244,6 +244,20 @@ def test_redirect_without_preload_releases_connection(self) -> None:
             assert r._pool.num_connections == 1
             assert len(http.pools) == 1
 
+    def test_303_redirect_makes_request_lose_body(self) -> None:
+        with PoolManager() as http:
+            response = http.request(
+                "POST",
+                f"{self.base_url}/redirect",
+                fields={
+                    "target": f"{self.base_url}/headers_and_params",
+                    "status": "303 See Other",
+                },
+            )
+        data = response.json()
+        assert data["params"] == {}
+        assert "Content-Type" not in HTTPHeaderDict(data["headers"])
+
     def test_unknown_scheme(self) -> None:
         with PoolManager() as http:
             unknown_scheme = "unknown"