FreeSWITCH: Pre-authentication out-of-bounds writes in mod_xml_rpc WebSocket frame parsing

Overview

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. Prior to 1.11.2, ws_read_frame() unmasked a WebSocket payload by iterating wsh->datalen, which included frame headers, while indexing from the payload pointer. A masked frame filling the 64 KiB receive buffer could therefore XOR up to 14 bytes beyond the buffer, and the exact-capacity case also wrote a terminating NUL one byte out of bounds. The flaw is reachable before authentication when mod_xml_rpc and its opt-in WebSocket endpoint are enabled, while both features are disabled in the stock configuration. The writes remain within the same connection handle's adjacent outbound buffer, so neither a process crash nor cross-session disclosure has been demonstrated. This issue is fixed in version 1.11.2.

Affected

• freeswitch < 1.11.2

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.