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[3.6] bpo-39503: CVE-2020-8492: Fix AbstractBasicAuthHandler#19299

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[3.6] bpo-39503: CVE-2020-8492: Fix AbstractBasicAuthHandler#19299
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@tapakund tapakund commented Apr 2, 2020

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 Ben Caller
and Matt Schwager.

AbstractBasicAuthHandler of urllib.request now parses all
WWW-Authenticate HTTP headers and accepts multiple challenges per
header: use the realm of the first Basic challenge.

Co-Authored-By: Serhiy Storchaka storchaka@gmail.com

Signed-off-by: Tapas Kundu tkundu@vmware.com

https://bugs.python.org/issue39503

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 Ben Caller
and Matt Schwager.

AbstractBasicAuthHandler of urllib.request now parses all
WWW-Authenticate HTTP headers and accepts multiple challenges per
header: use the realm of the first Basic challenge.

Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>

Co-authored-by: Victor Stinner vstinner@python.org

Signed-off-by: Tapas Kundu <tkundu@vmware.com>
@tapakund
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tapakund commented Apr 2, 2020

@vstinner pls review.

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vstinner commented Apr 2, 2020

Sorry but I prefer to backport security fixes myself. I created PR #19304.

@vstinner vstinner closed this Apr 2, 2020
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