The updated advisory is a follow-up to the original advisory titled ICSA-21-266-01 Trane Symbio that was published on September 23, 2021, to the ICS webpage on us-cert.cisa.gov. This advisory contains mitigations for a Code Injection vulnerability in Trane Symbio 700 and Symbio 800 controllers.
https://us-cert.cisa.gov/ics/advisories/icsa-21-266-01