The AWV and MiCollab Client Service components in Mitel MiCollab before 9.3 could allow an attacker to perform a Man-In-the-Middle attack by sending multiple session renegotiation requests, due to insufficient TLS session controls. A successful exploit could allow an attacker to modify application data and state.
https://www.mitel.com/support/security-advisories/mitel-product-security-advisory-21-0005