From 93742fbb8de75c036b552294fc2bd73eafa47592 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Wed, 7 Apr 2021 04:45:05 -0700
Subject: [PATCH 27/30] bpo-43075: Fix ReDoS in urllib AbstractBasicAuthHandler
 (GH-24391)
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Fix Regular Expression Denial of Service (ReDoS) vulnerability in
urllib.request.AbstractBasicAuthHandler. The ReDoS-vulnerable regex
has quadratic worst-case complexity and it allows cause a denial of
service when identifying crafted invalid RFCs. This ReDoS issue is on
the client side and needs remote attackers to control the HTTP server.
(cherry picked from commit 7215d1ae25525c92b026166f9d5cac85fb1defe1)

Co-authored-by: Yeting Li <liyt@ios.ac.cn>
(backported to Python 2.7 by Michał Górny)
---
 Lib/urllib2.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/urllib2.py b/Lib/urllib2.py
index b2d1fad6f2..c92fb6afb8 100644
--- a/Lib/urllib2.py
+++ b/Lib/urllib2.py
@@ -858,7 +858,7 @@ class AbstractBasicAuthHandler:
     # (single quotes are a violation of the RFC, but appear in the wild)
     rx = re.compile('(?:^|,)'   # start of the string or ','
                     '[ \t]*'    # optional whitespaces
-                    '([^ \t]+)' # scheme like "Basic"
+                    '([^ \t,]+)' # scheme like "Basic"
                     '[ \t]+'    # mandatory whitespaces
                     # realm=xxx
                     # realm='xxx'
-- 
2.32.0

