CVE-2026-49840

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, esl_recv_event() parses Content-Length with atol() and passes the result straight to malloc(len + 1) with no sign or magnitude check. A malicious or man-in-the-middle ESL peer can send a frame with a negative Content-Length to corrupt the heap of, or crash, any process linked against libesl, before the client has authenticated to that peer. This issue has been patched in version 1.11.1.

• CWE-20
• CWE-122
• CWE-195
• CWE-787

• https://github.com/signalwire/freeswitch/releases/tag/v1.11.1Release Notes
• https://github.com/signalwire/freeswitch/security/advisories/GHSA-g597-9fgg-ghg9Third Party Advisory

Published

Jun 9, 2026

Last Modified

Jul 23, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
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