Debian 10020 Published by

A python2.7 security update has been released for Debian GNU/Linux 11 to address multiple security issues that could result in command injection, denial of service (DoS), request smuggling, and port scanning.

DLA 3432-1: python2.7 security update

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Debian LTS Advisory DLA-3432-1 Sylvain Beucler
May 24, 2023
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Package : python2.7
Version : 2.7.16-2+deb10u2
CVE ID : CVE-2015-20107 CVE-2019-20907 CVE-2020-8492 CVE-2020-26116
CVE-2021-3177 CVE-2021-3733 CVE-2021-3737 CVE-2021-4189
Debian Bug : 970099

Multiple security issues were discovered in Python, an interactive
high-level object-oriented language. An attacker may cause command
injection, denial of service (DoS), request smuggling and port


The mailcap module does not add escape characters into commands
discovered in the system mailcap file. This may allow attackers to
inject shell commands into applications that call
mailcap.findmatch with untrusted input (if they lack validation of
user-provided filenames or arguments).


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


Python allows an HTTP server to conduct Regular Expression Denial
of Service (ReDoS) attacks against a client because of
urllib.request.AbstractBasicAuthHandler catastrophic backtracking.


http.client 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


Python 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.


There's a flaw in urllib's AbstractBasicAuthHandler class. An
attacker who controls a malicious HTTP server that an HTTP client
(such as web browser) connects to, could trigger a Regular
Expression Denial of Service (ReDOS) during an authentication
request with a specially crafted payload that is sent by the
server to the client.


An improperly handled HTTP response in the HTTP client code of
python may allow a remote attacker, who controls the HTTP server,
to make the client script enter an infinite loop, consuming CPU


The FTP (File Transfer Protocol) client library in PASV (passive)
mode trusts the host from the PASV response by default. This flaw
allows an attacker to set up a malicious FTP server that can trick
FTP clients into connecting back to a given IP address and
port. This vulnerability could lead to FTP client scanning
ports. For the rare user who wants the previous behavior, set a
`trust_server_pasv_ipv4_address` attribute on your `ftplib.FTP`
instance to True.


An unnecessary quadratic algorithm exists in one path when
processing some inputs to the IDNA (RFC 3490) decoder, such that a
crafted, unreasonably long name being presented to the decoder
could lead to a CPU denial of service.

For Debian 10 buster, these problems have been fixed in version

We recommend that you upgrade your python2.7 packages.

For the detailed security status of python2.7 please refer to
its security tracker page at:

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: