FreeSWITCH is an open-source software telecommunications platform. From 1.10.0 until 1.11.1, a stack-based buffer overflow in mod_sofia when generating dialog-event notifications. A peer can establish a dialog with an excessively long SIP To-header user part and subsequently subscribe to that entity’s dialog events, causing the stored value to overflow a fixed-size stack buffer. Exploitation requires presence or shared-appearance management to be enabled and normally requires valid profile credentials, unless subscription authentication is disabled. The overflow can terminate the FreeSWITCH process and all active calls. This vulnerability is fixed in version 1.11.2.