MGASA-2021-0435

bpo-42278: Replaced usage of tempfile.mktemp() with TemporaryDirectory to avoid a potential race condition.

bpo-44394: Update the vendored copy of libexpat to 2.4.1 (from 2.2.8) to get the fix for the CVE-2013-0340 “Billion Laughs” vulnerability. This copy is most used on Windows and macOS.

bpo-43124: Made the internal putcmd function in smtplib sanitize input for presence of \r and \n characters to avoid (unlikely) command injection.

bpo-36384: ipaddress module no longer accepts any leading zeros in IPv4 address strings. Leading zeros are ambiguous and interpreted as octal notation by some libraries. For example the legacy function socket.inetaton() treats leading zeros as octal notation. glibc implementation of modern inetpton() does not accept any leading zeros. For a while the ipaddress module used to accept ambiguous leading zeros.

It was discovered that Python incorrectly handled certain RFCs. An attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 16.04 ESM. (CVE-2021-3733)

It was discovered that Python incorrectly handled certain server responses. An attacker could possibly use this issue to cause a denial of service. (CVE-2021-3737)