---
id: "CVE-2026-116780"
kind: "vulnerability"
aliases: ["CVE-2026-116780"]
title: "FreeSWITCH: out-of-bounds read leaks adjacent heap memory via event expansion"
severity: "low"
cvss: 2.7
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["freeswitch", "runtime", "self-hosted", "telecom"]
not_affected_if: ["fixed-version-1.11.2-or-later", "no-event-socket-exposure"]
published_at: "2026-11-05T20:17:44+00:00"
first_seen_at: "2026-11-05T20:40:45+00:00"
updated_at: "2026-11-05T20:43:35+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116780", "first_seen_at": "2026-11-05T20:40:45+00:00"}]
exploit_sources: []
---

# FreeSWITCH: out-of-bounds read leaks adjacent heap memory via event expansion

FreeSWITCH before 1.11.2 reads past a heap buffer when expanding a variable with a positive offset, appending adjacent heap memory to the output. An attacker can read leaked channel variables, credentials or pointer bytes, mainly through configuration templates or authenticated Event Socket eval and expand commands.

_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 the installed package version.
- Look for configuration templates that slice remote input with `${variable:offset}` syntax.
- Check whether the Event Socket interface is enabled and who can authenticate to it.

## Fix

- FreeSWITCH: upgrade to `1.11.2`

## Timeline

- 2026-11-05T20:40:45+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116780

## Documents

- [advisory] Vendor advisory: github.com https://github.com/signalwire/freeswitch/security/advisories/GHSA-2p6g-9c8q-232p
- [fix] Patch: github.com https://github.com/signalwire/freeswitch/commit/30cdb387ae0fac0cbbeb6ac05416aaffb9252258
- [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_event_expand_headers_check() advanced beyond its heap copy when a positive offset in ${variable:offset} exceeded the variable value's length. The following length calculation and copy appended adjacent heap memory to the expansion result, potentially exposing channel variables, credentials, allocator data, and pointer bytes. The flaw is reachable through configuration templates that slice remote input and through authenticated Event Socket eval or Event Socket expand commands; the separate channel-variable expander used by ordinary dialplan slicing is unaffected. The requester cannot choose adjacent memory and disclosure stops at a zero byte, but repeated expansion can influence the layout. This issue is fixed in version 1.11.2.

---

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