Apache Guacamole 1.1.0 and older may mishandle pointers involved inprocessing data received via RDP static virtual channels. If a userconnects to a malicious or compromised RDP server, a series ofspecially-crafted PDUs could result in memory corruption, possiblyallowing arbitrary code to be executed with the privileges of therunning guacd process.
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