---
id: CVE-2026-53450
title: Coturn is a free open source implementation of TURN and STUN Server
summary: >-
  Coturn is a free open source implementation of TURN and STUN Server. Prior to
  4.13.0, coturn rejects loopback peers by default unless allow-loopback-peers
  is enabled, but the default loopback guard can be bypassed by using the
  IPv4-mappe…
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L'
cwe:
  - CWE-918
published: '2026-07-10'
updated: '2026-07-10'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53450'
references:
  - url: >-
      https://github.com/coturn/coturn/commit/b057acbebe721c8f2f202ddad5e16289e295c754
    label: security-advisories@github.com
  - url: 'https://github.com/coturn/coturn/security/advisories/GHSA-w4hf-cr3w-6h79'
    label: security-advisories@github.com
  - url: 'https://github.com/coturn/coturn/security/advisories/GHSA-w4hf-cr3w-6h79'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.0029
epssPercentile: 0.19173
ingestedAt: '2026-07-11T20:15:26.210Z'
---

## Overview

Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.13.0, coturn rejects loopback peers by default unless allow-loopback-peers is enabled, but the default loopback guard can be bypassed by using the IPv4-mapped IPv6 peer address ::ffff:127.0.0.1 in a TURN XOR-PEER-ADDRESS attribute. ioa_addr_is_loopback checks for the literal IPv6 loopback shape before IPv4-mapped IPv6 handling, so good_peer_addr does not apply the default loopback rejection and an authenticated TURN client can expose services bound only to localhost on the coturn host through TURN relay traffic. This issue is fixed in version 4.13.0.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.