There is 1 open security issue in buster.
1 issue left for the package maintainer to handle:
markdown2 >=188.8.131.52, fixed in 2.4.0, is affected by a regular expression denial of service vulnerability. If an attacker provides a malicious string, it can make markdown2 processing difficult or delayed for an extended period of time.
You can find information about how to handle this issue in the security team's documentation.