---
id: "CVE-2026-116574"
kind: "vulnerability"
aliases: ["CVE-2026-116574"]
title: "FreeSWITCH: one-byte heap overflow in XML encoding can crash the process"
severity: "medium"
cvss: 5.9
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["freeswitch", "package", "self-hosted", "telecom", "voip"]
not_affected_if: ["fixed-version", "no-remote-input", "no-xml-cdr"]
published_at: "2026-11-05T19:17:11+00:00"
first_seen_at: "2026-11-05T19:40:35+00:00"
updated_at: "2026-11-05T19:43:27+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116574", "first_seen_at": "2026-11-05T19:40:35+00:00"}]
exploit_sources: []
---

# FreeSWITCH: one-byte heap overflow in XML encoding can crash the process

FreeSWITCH before 1.11.2 writes a terminating zero one byte past a heap buffer when it XML-encodes remote-supplied text at a buffer boundary. An attacker can crash the process or corrupt an adjacent object; 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` or `freeswitch -version`.
- Look for `mod_xml_cdr`, conference or formatted CDR XML, or XML Event Socket output in the configuration.

## Fix

- FreeSWITCH: upgrade to `1.11.2`.

## Timeline

- 2026-11-05T19:40:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116574

## Documents

- [advisory] Vendor advisory: github.com https://github.com/signalwire/freeswitch/security/advisories/GHSA-r6vh-qmwm-h3cc
- [fix] Patch: github.com https://github.com/signalwire/freeswitch/commit/28fcfd26246c112fa4b9e698433d09e4836ca1b5
- [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, switch_xml_ampencode() reserved only ten bytes for the widest numeric character reference produced from a four-byte UTF-8 sequence, omitting space for the terminating NUL. When remote-supplied text was serialized at the exact buffer-growth boundary, the terminator wrote one byte beyond the heap allocation. Reachable surfaces include mod_xml_cdr, conference and formatted CDR XML, XML Event Socket output, and XML API output that serializes caller-controlled values. The fixed zero-byte write can abort the process or truncate an adjacent object, while remote code execution has not been demonstrated. This issue is fixed in version 1.11.2.

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