---
id: "CVE-2026-116787"
kind: "vulnerability"
aliases: ["CVE-2026-116787"]
title: "FreeSWITCH: unauthenticated Event Socket header crashes the telephony process"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["freeswitch", "runtime", "self-hosted", "telephony"]
not_affected_if: ["default-config", "fixed-version", "no-event-socket"]
published_at: "2026-11-05T20:17:46+00:00"
first_seen_at: "2026-11-05T20:40:46+00:00"
updated_at: "2026-11-05T20:43:02+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116787", "first_seen_at": "2026-11-05T20:40:46+00:00"}]
exploit_sources: []
---

# FreeSWITCH: unauthenticated Event Socket header crashes the telephony process

A malformed Content-Length header on FreeSWITCH's Event Socket module, parsed before authentication, can overflow an allocation and make the process abort. Any host allowed by the inbound ACL can stop the service with one packet, dropping all active calls until restart.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the FreeSWITCH version with `fs_cli -x version` or `freeswitch -version`
- Check whether mod_event_socket is loaded and what `apply-inbound-acl` allows in `event_socket.conf.xml`
- Check whether outbound socket dialplan connects to application servers you do not control

## Fix

- FreeSWITCH: move to `1.11.2` or later

## Timeline

- 2026-11-05T20:40:46+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116787

## Documents

- [advisory] Vendor advisory: github.com https://github.com/signalwire/freeswitch/security/advisories/GHSA-j27c-m99r-8pc3
- [fix] Patch: github.com https://github.com/signalwire/freeswitch/commit/a097e124213c164845dcaaa8feed2e70bc1e7191
- [fix] Release notes: github.com https://github.com/signalwire/freeswitch/releases/tag/v1.11.2

## From the sources

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, mod_event_socket used an unauthenticated Content-Length value directly as the allocation size for an Event Socket message body. Negative or extremely large values could overflow the terminator calculation or force an allocation failure through a helper that aborts the FreeSWITCH process. The header is parsed before the Event Socket password, so any host admitted by apply-inbound-acl can trigger termination with its first packet; the default loopback ACL limits ordinary installations to local clients. The outbound socket dialplan path is also affected when FreeSWITCH connects to a hostile application server, and process termination drops every active call until the service is restarted. This issue is fixed in version 1.11.2.

---

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