From d71ab28f104cac824c6036fa9b35cc2e2dd19bf8 Mon Sep 17 00:00:00 2001
From: Lumir Balhar <lbalhar@redhat.com>
Date: Tue, 12 Dec 2023 11:06:20 +0100
Subject: [PATCH] Security fix for CVE-2023-45803

---
 src/urllib3/_collections.py   | 18 ++++++++++++++++++
 src/urllib3/connectionpool.py |  5 +++++
 src/urllib3/poolmanager.py    |  7 +++++--
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/urllib3/_collections.py b/src/urllib3/_collections.py
index da9857e..bceb845 100644
--- a/src/urllib3/_collections.py
+++ b/src/urllib3/_collections.py
@@ -268,6 +268,24 @@ class HTTPHeaderDict(MutableMapping):
         else:
             return vals[1:]
 
+    def _prepare_for_method_change(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
diff --git a/src/urllib3/connectionpool.py b/src/urllib3/connectionpool.py
index 4018321..8f9ebb5 100644
--- a/src/urllib3/connectionpool.py
+++ b/src/urllib3/connectionpool.py
@@ -36,6 +36,7 @@ from .exceptions import (
 from .packages import six
 from .packages.six.moves import queue
 from .packages.ssl_match_hostname import CertificateError
+from ._collections import HTTPHeaderDict
 from .request import RequestMethods
 from .response import HTTPResponse
 from .util.connection import is_connection_dropped
@@ -800,7 +801,11 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
         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)
diff --git a/src/urllib3/poolmanager.py b/src/urllib3/poolmanager.py
index 3a31a28..7d4c22c 100644
--- a/src/urllib3/poolmanager.py
+++ b/src/urllib3/poolmanager.py
@@ -4,7 +4,7 @@ import collections
 import functools
 import logging
 
-from ._collections import RecentlyUsedContainer
+from ._collections import HTTPHeaderDict, RecentlyUsedContainer
 from .connectionpool import HTTPConnectionPool, HTTPSConnectionPool, port_by_scheme
 from .exceptions import (
     LocationValueError,
@@ -381,9 +381,12 @@ class PoolManager(RequestMethods):
         # 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):
-- 
2.43.0