Arch Linux Security Advisory ASA-202102-37
==========================================

Severity: Medium
Date    : 2021-02-27
CVE-ID  : CVE-2021-3177 CVE-2021-23336
Package : python
Type    : multiple issues
Remote  : Yes
Link    : https://security.archlinux.org/AVG-1465

Summary
=======

The package python before version 3.9.2-1 is vulnerable to multiple
issues including arbitrary code execution and url request injection.

Resolution
==========

Upgrade to 3.9.2-1.

# pacman -Syu "python>=3.9.2-1"

The problems have been fixed upstream in version 3.9.2.

Workaround
==========

None.

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

- CVE-2021-3177 (arbitrary code execution)

Python 3.x through 3.9.1 has a buffer overflow in PyCArg_repr in
_ctypes/callproc.c, which may lead to remote code execution in certain
Python applications that accept floating-point numbers as untrusted
input, as demonstrated by a 1e300 argument to c_double.from_param. This
occurs because sprintf is used unsafely.

- CVE-2021-23336 (url request injection)

The package python/cpython from 0 and before 3.6.13, from 3.7.0 and
before 3.7.10, from 3.8.0 and before 3.8.8, from 3.9.0 and before 3.9.2
are vulnerable to Web Cache Poisoning via urllib.parse.parse_qsl and
urllib.parse.parse_qs by using a vector called parameter cloaking. When
the attacker can separate query parameters using a semicolon (;), they
can cause a difference in the interpretation of the request between the
proxy (running with default configuration) and the server. This can
result in malicious requests being cached as completely safe ones, as
the proxy would usually not see the semicolon as a separator, and
therefore would not include it in a cache key of an unkeyed parameter.

The package python-django contains a copy of urllib.parse.parse_qsl()
which was added to backport some security fixes. A further security fix
has been issued in versions 3.1.7, 3.0.13 and 2.2.19 such that
parse_qsl() no longer allows using ; as a query parameter separator by
default.

Impact
======

A malicious format string could execute code and a malicious user could
send crafted HTTP queries poisoning the cache.

References
==========

https://python-security.readthedocs.io/vuln/ctypes-buffer-overflow-pycarg_repr.html
https://bugs.python.org/issue42938
https://github.com/python/cpython/pull/24239
https://github.com/python/cpython/commit/c347cbe694743cee120457aa6626712f7799a932
https://snyk.io/vuln/SNYK-UPSTREAM-PYTHONCPYTHON-1074933
https://snyk.io/blog/cache-poisoning-in-popular-open-source-packages/
https://bugs.python.org/issue42967
https://github.com/python/cpython/pull/24297
https://github.com/python/cpython/commit/c9f07813ab8e664d8c34413c4fc2d4f86c061a92
https://www.djangoproject.com/weblog/2021/feb/19/security-releases/
https://github.com/django/django/commit/8f6d431b08cbb418d9144b976e7b972546607851
https://security.archlinux.org/CVE-2021-3177
https://security.archlinux.org/CVE-2021-23336