diff --git a/changelog.d/17675.feature b/changelog.d/17675.feature
new file mode 100644
index 000000000..20db149ca
--- /dev/null
+++ b/changelog.d/17675.feature
@@ -0,0 +1 @@
+Guests can use the new media endpoints to download media, as described by [MSC4189](https://github.com/matrix-org/matrix-spec-proposals/pull/4189).
\ No newline at end of file
diff --git a/synapse/rest/client/media.py b/synapse/rest/client/media.py
index c30e3022d..25b302370 100644
--- a/synapse/rest/client/media.py
+++ b/synapse/rest/client/media.py
@@ -138,7 +138,7 @@ class ThumbnailResource(RestServlet):
     ) -> None:
         # Validate the server name, raising if invalid
         parse_and_validate_server_name(server_name)
-        await self.auth.get_user_by_req(request)
+        await self.auth.get_user_by_req(request, allow_guest=True)
 
         set_cors_headers(request)
         set_corp_headers(request)
@@ -229,7 +229,7 @@ class DownloadResource(RestServlet):
         # Validate the server name, raising if invalid
         parse_and_validate_server_name(server_name)
 
-        await self.auth.get_user_by_req(request)
+        await self.auth.get_user_by_req(request, allow_guest=True)
 
         set_cors_headers(request)
         set_corp_headers(request)