The man package includes tools for finding information and documentation about commands on a system.
Versions of man before 1.51 have a bug where a malformed man file can cause a program named "unsafe" to be run. To exploit this vulnerability a local attacker would need to be able to get a victim to run man on a carefully crafted man file, and for the attacker to be able to create a file called "unsafe" that will be on the victim's default path.
Users of man can upgrade to these erratum packages which contain a patch to correct this vulnerability. These erratum packages also contain fixes for a number of other bugs.