Arch Linux Security Advisory ASA-202103-27

Severity: High
Date    : 2021-03-25
CVE-ID  : CVE-2019-20907 CVE-2020-8492  CVE-2020-26116 CVE-2020-27619
          CVE-2021-3177  CVE-2021-23336
Package : python2
Type    : multiple issues
Remote  : Yes
Link    :


The package python2 before version 2.7.18-3 is vulnerable to multiple
issues including arbitrary code execution, url request injection and
denial of service.


Upgrade to 2.7.18-3.

# pacman -Syu "python2>=2.7.18-3"

The problems have been fixed upstream but no release is available yet.




- CVE-2019-20907 (denial of service)

In Lib/ in Python through 3.8.3, an attacker is able to craft
a TAR archive leading to an infinite loop when opened by,
because _proc_pax lacks header validation.

- CVE-2020-8492 (denial of service)

Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7
through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct
Regular Expression Denial of Service (ReDoS) attacks against a client
because of urllib.request.AbstractBasicAuthHandler catastrophic

- CVE-2020-26116 (url request injection)

http.client in Python 3.x before 3.5.10, 3.6.x before 3.6.12, 3.7.x
before 3.7.9, and 3.8.x before 3.8.5 allows CRLF injection if the
attacker controls the HTTP request method, as demonstrated by inserting
CR and LF control characters in the first argument of

- CVE-2020-27619 (arbitrary code execution)

In Python 3 through 3.9.0, the Lib/test/ CJK
codec tests call eval() on content retrieved via HTTP.

- 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


A remote attacker could execute code or crash the application through
crafted files or HTTP requests. Furthermore, a remote attacker could
inject arbitrary headers or poison web caches through crafted HTTP