[ASA-202102-35] python-httplib2: denial of service

[Morten Linderud]

Arch Linux Security Advisory ASA-202102-35
==========================================

Severity: Medium
Date    : 2021-02-27
CVE-ID  : CVE-2021-21240
Package : python-httplib2
Type    : denial of service
Remote  : Yes
Link    : https://security.archlinux.org/AVG-1546

Summary
=======

The package python-httplib2 before version 0.19.0-1 is vulnerable to
denial of service.

Resolution
==========

Upgrade to 0.19.0-1.

# pacman -Syu "python-httplib2>=0.19.0-1"

The problem has been fixed upstream in version 0.19.0.

Workaround
==========

The issue can be mitigated by using
"httplib2.USE_WWW_AUTH_STRICT_PARSING = True".

Description
===========

In python-httplib2 before version 0.19.0, a malicious server which
responds with a long series of "\xa0" characters in the "www-
authenticate" header may cause Denial of Service (CPU burn while
parsing header) of the httplib2 client accessing said server. This is
fixed in version 0.19.0 which contains a new implementation of auth
headers parsing using the pyparsing library.

Impact
======

A malicious server can crash the application with crafted HTTP
responses.

References
==========

https://github.com/httplib2/httplib2/security/advisories/GHSA-93xj-8mrv-444m
https://github.com/httplib2/httplib2/pull/182
https://github.com/httplib2/httplib2/commit/bd9ee252c8f099608019709e22c0d705e98d26bc
https://security.archlinux.org/CVE-2021-21240
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