CVE-2020-1747

Name	CVE-2020-1747
Description	A vulnerability was discovered in the PyYAML library in versions before 5.3.1, where it is susceptible to arbitrary code execution when it processes untrusted YAML files through the full_load method or with the FullLoader loader. Applications that use the library to process untrusted input may be vulnerable to this flaw. An attacker could use this flaw to execute arbitrary code on the system by abusing the python/object/new constructor.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severity	high
Debian Bugs	953013

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
pyyaml (PTS)	stretch	3.12-1	fixed
	buster	3.13-2	fixed
	bullseye	5.3.1-5	fixed
	bookworm, sid	5.4.1-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Debian Bugs
pyyaml	source	jessie	(not affected)
pyyaml	source	stretch	(not affected)
pyyaml	source	buster	(not affected)
pyyaml	source	(unstable)	5.3-2	953013

Notes

[buster] - pyyaml <not-affected> (Loader/Constructor classes are unsafe in this version)
[stretch] - pyyaml <not-affected> (Loader/Constructor classes are unsafe in this version)
[jessie] - pyyaml <not-affected> (Loader/Constructor classes are unsafe in this version)
https://github.com/yaml/pyyaml/pull/386