Description
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.
Published: 2026-06-09
Score: 9.1 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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History

Wed, 10 Jun 2026 15:15:00 +0000

Type Values Removed Values Added
First Time appeared Freeswitch
Freeswitch freeswitch
CPEs cpe:2.3:a:freeswitch:freeswitch:*:*:*:*:*:*:*:*
Vendors & Products Freeswitch
Freeswitch freeswitch

Tue, 09 Jun 2026 19:00:00 +0000

Type Values Removed Values Added
First Time appeared Signalwire
Signalwire freeswitch
Vendors & Products Signalwire
Signalwire freeswitch

Tue, 09 Jun 2026 17:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 09 Jun 2026 16:30:00 +0000

Type Values Removed Values Added
Description 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.
Title FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing
Weaknesses CWE-122
CWE-195
CWE-20
CWE-787
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H'}


Subscriptions

Freeswitch Freeswitch
Signalwire Freeswitch
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-09T17:00:21.313Z

Reserved: 2026-06-01T18:50:36.056Z

Link: CVE-2026-49840

cve-icon Vulnrichment

Updated: 2026-06-09T17:00:09.680Z

cve-icon NVD

Status : Analyzed

Published: 2026-06-09T17:17:47.703

Modified: 2026-06-10T15:06:24.257

Link: CVE-2026-49840

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-09T18:45:06Z