Apache Guacamole 1.1.0 and older do not properly validate datareceived from RDP servers via static virtual channels. If a userconnects to a malicious or compromised RDP server, specially-craftedPDUs could result in disclosure of information within the memory ofthe guacd process handling the connection.
https://research.checkpoint.com/2020/apache-guacamole-rce/
https://lists.debian.org/debian-lts-announce/2020/11/msg00010.html
https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44525