PT-2026-47847 · Signalwire · Freeswitch

Published 2026-06-09 · Updated 2026-06-09 · CVE-2026-49840

Mitre

CVSS v3.1

9.1

Critical

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

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.

Fix

RCE

Heap Based Buffer Overflow

Memory Corruption

Weakness Enumeration

CWE-20

CWE-122

CWE-195

CWE-787

Related Identifiers

CVE-2026-49840

Affected Products

Freeswitch

References · 3

• https://nvd.nist.gov/vuln/detail/CVE-2026-49840 · Security Note
• https://github.com/signalwire/freeswitch/security/advisories/GHSA-g597-9fgg-ghg9 · Note
• https://github.com/signalwire/freeswitch/releases/tag/v1.11.1 · Note