Sks Keyserver Project » Sks Keyserver : Security Vulnerabilities, CVEs,

Interaction between the sks-keyserver code through 1.2.0 of the SKS keyserver network, and GnuPG through 2.2.16, makes it risky to have a GnuPG keyserver configuration line referring to a host on the SKS keyserver network. Retrieving data from this network may cause a persistent denial of service, because of a Certificate Spamming Attack.

Cross-site scripting (XSS) vulnerability in wserver.ml in SKS Keyserver before 1.1.5 allows remote attackers to inject arbitrary web script or HTML via the PATH_INFO to pks/lookup/undefined1.