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python-tornado/SOURCES/0002-PATCH-web-Fix-an-open-...

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From bcae82a6dd7bfed280559c8920dd89d4a48fa021 Mon Sep 17 00:00:00 2001
From: Ben Darnell <ben@bendarnell.com>
Date: Tue, 25 Jul 2023 06:39:23 -0400
Subject: [PATCH 2/2] [PATCH] web: Fix an open redirect in StaticFileHandler
Under some configurations the default_filename redirect could be exploited
to redirect to an attacker-controlled site. This change refuses to redirect
to URLs that could be misinterpreted.
A test case for the specific vulnerable configuration will follow after the
patch has been available.
Originally from upstream:
- https://github.com/tornadoweb/tornado/commit/8f35b31ab
---
tornado/web.py | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/tornado/web.py b/tornado/web.py
index 546e6ec..8410880 100644
--- a/tornado/web.py
+++ b/tornado/web.py
@@ -2771,6 +2771,15 @@ class StaticFileHandler(RequestHandler):
# but there is some prefix to the path that was already
# trimmed by the routing
if not self.request.path.endswith("/"):
+ if self.request.path.startswith("//"):
+ # A redirect with two initial slashes is a "protocol-relative" URL.
+ # This means the next path segment is treated as a hostname instead
+ # of a part of the path, making this effectively an open redirect.
+ # Reject paths starting with two slashes to prevent this.
+ # This is only reachable under certain configurations.
+ raise HTTPError(
+ 403, "cannot redirect path with two initial slashes"
+ )
self.redirect(self.request.path + "/", permanent=True)
return None
absolute_path = os.path.join(absolute_path, self.default_filename)
--
2.39.3