File CVE-2020-8492-urllib-ReDoS.patch of Package python3

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File CVE-2020-8492-urllib-ReDoS.patch of Package python3 (Revision db96c2ebb16e8cfc5e53652a2aea02b2)

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From 34e25a97709a05f7c804036dd1e16afda6bdfa33 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Thu, 30 Jan 2020 16:13:03 +0100
Subject: [PATCH 1/2] bpo-39503: Fix urllib basic auth regex

The AbstractBasicAuthHandler class of the urllib.request module uses
an inefficient regular expression which can be exploited by an
attacker to cause a denial of service. Fix the regex to prevent the
catastrophic backtracking.

Vulnerability reported by Matt Schwager.
---
 Lib/urllib2.py                                                     |    2 +-
 Misc/NEWS.d/next/Security/2020-01-30-16-15-29.bpo-39503.B299Yq.rst |    4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Security/2020-01-30-16-15-29.bpo-39503.B299Yq.rst

--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2020-01-30-16-15-29.bpo-39503.B299Yq.rst
@@ -0,0 +1,4 @@
+CVE-2020-8492: The :class:`~urllib.request.AbstractBasicAuthHandler` class of the
+:mod:`urllib.request` module uses an inefficient regular expression which can
+be exploited by an attacker to cause a denial of service. Fix the regex to
+prevent the catastrophic backtracking. Vulnerability reported by Matt Schwager.
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -945,7 +945,7 @@ class AbstractBasicAuthHandler:
 
     # allow for double- and single-quoted realm values
     # (single quotes are a violation of the RFC, but appear in the wild)
-    rx = re.compile('(?:.*,)*[ \t]*([^ \t]+)[ \t]+'
+    rx = re.compile('(?:[^,]*,)*[ \t]*([^ \t]+)[ \t]+'
                     'realm=(["\']?)([^"\']*)\\2', re.I)
 
     # XXX could pre-emptively send auth info already accepted (RFC 2617,

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