CVE-2026-49840

CVE-2026-49840 affects FreeSWITCH libesl before version 1.11.1. The flaw occurs in esl_recv_event(): Content-Length is parsed with atol() and the result is passed to malloc(len + 1) without sign or magnitude checks, allowing a pre-authentication, remote attacker to corrupt the heap or crash the p...

CVE-2026-49840 FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing

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 version 1.11.1, eslrecvevent parses Content-Length with atol and passes the result straight to malloclen ...