The vulnerability is a stack-based buffer overflow in the mod_sofia module of FreeSWITCH. The flaw occurs during the processing of dialog-event notifications when an attacker sends a SIP request containing an overly long To-header user field. The overflow can corrupt the stack and terminate the FreeSWITCH process, causing the loss of all active calls. The weakness aligns with CWE‑121 stack buffer overflow and may provide a path to arbitrary code execution, though the documented impact is a crash.

The flaw affects SignalWire’s FreeSWITCH product from version 1.10.0 through 1.11.1 inclusive. Version 1.11.2 and later include a defensive change that sanitizes the To-header user field and eliminates the overflow. The issue requires that presence or shared‑appearance management be enabled and, in most configurations, that the subscriber provide profile credentials unless subscription authentication is disabled.

The CVSS v3 base score is 6.5, indicating a medium impact. EPSS is not available, and the vulnerability is not currently listed in CISA’s KEV catalog. An attacker would need to send crafted SIP traffic to a target running an affected FreeSWITCH instance and establish a dialog subscription, which can be achieved over the network from any host that can reach the SIP interface. If present, the required authentication controls can mitigate the risk.