---
id: "CVE-2026-116785"
kind: "vulnerability"
aliases: ["CVE-2026-116785"]
title: "FreeSWITCH: WebSocket frame length overflow lets unauthenticated clients corrupt memory"
severity: "critical"
cvss: 9.1
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["freeswitch", "runtime", "telecom", "voip", "websocket"]
not_affected_if: ["default-config", "fixed-1.11.2-or-later", "mod-xml-rpc-disabled", "websocket-disabled"]
published_at: "2026-11-05T20:17:45+00:00"
first_seen_at: "2026-11-05T20:40:45+00:00"
updated_at: "2026-11-05T20:42:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116785", "first_seen_at": "2026-11-05T20:40:45+00:00"}]
exploit_sources: []
---

# FreeSWITCH: WebSocket frame length overflow lets unauthenticated clients corrupt memory

FreeSWITCH before 1.11.2 mishandles 64-bit WebSocket payload lengths in ws_read_frame(), causing a heap overwrite past a 64 KiB buffer. An unauthenticated remote client can crash FreeSWITCH and end all concurrent sessions; remote code execution has not been demonstrated.

_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` and confirm whether it is below `1.11.2`.
- Check whether mod_xml_rpc is loaded and its WebSocket `/socket` endpoint is enabled in the mod_xml_rpc configuration.
- Confirm whether the service is reachable from untrusted networks.

## Fix

- FreeSWITCH: move to `1.11.2` or later.

## Timeline

- 2026-11-05T20:40:45+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116785

## Documents

- [advisory] Vendor advisory: github.com https://github.com/signalwire/freeswitch/security/advisories/GHSA-jj89-q47c-gh94
- [fix] Patch: github.com https://github.com/signalwire/freeswitch/commit/d557ca6d29e6da4f10824dc158100906a592b91a
- [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, ws_read_frame() decoded a WebSocket frame's 64-bit extended payload length with a 32-bit byte swap and narrowed the result into a signed length. A value whose surviving low word became negative bypassed the signed size check and was reinterpreted as an enormous unsigned count, causing client bytes to overwrite memory beyond the 64 KiB receive buffer. Any client completing a /socket WebSocket upgrade on an enabled mod_xml_rpc endpoint reached the parser before HTTP authentication; both the module and WebSocket endpoint are disabled by default. The heap overwrite can corrupt connection pointers and crash FreeSWITCH, ending every concurrent session, although remote code execution has not been demonstrated. This issue is fixed in version 1.11.2.

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