---
id: CVE-2026-116567
title: >-
  FreeSWITCH: Pre-authentication stack buffer overflow in mod_rtmp
  control-message handling
summary: >-
  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, rtmp_handle_control()
  rendered an RTM…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-121
vendor: signalwire
product: freeswitch
affected:
  - freeswitch < 1.11.2
published: '2026-11-05'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T19:23:25.422Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-116567'
references:
  - url: >-
      https://github.com/signalwire/freeswitch/security/advisories/GHSA-hj6x-9653-p796
    label: >-
      https://github.com/signalwire/freeswitch/security/advisories/GHSA-hj6x-9653-p796
  - url: >-
      https://github.com/signalwire/freeswitch/commit/fc0db829b87d1a5a3043e355b4294c41851b13c6
    label: >-
      https://github.com/signalwire/freeswitch/commit/fc0db829b87d1a5a3043e355b4294c41851b13c6
  - url: 'https://github.com/signalwire/freeswitch/releases/tag/v1.11.2'
    label: 'https://github.com/signalwire/freeswitch/releases/tag/v1.11.2'
tags:
  - cve.org
ingestedAt: '2026-11-05T22:38:31.532Z'
---

## 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, rtmp_handle_control() rendered an RTMP user-control message into a 200-byte stack buffer using an unbounded sprintf loop controlled by the wire message length. A body of roughly 70 bytes or more overflowed the stack before any RTMP login, because the handshake authenticates neither side. The flaw affects deployments that build and load mod_rtmp, which is disabled in the stock build and configuration but commonly exposes a listener on TCP port 1935 when enabled. One unauthenticated message can crash FreeSWITCH and end every active call; the constrained ASCII hex output has not yielded control-flow hijacking. 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.