CVE-2026-53450

High

Description

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.

SeverityHigh

CVSS7.4

Exploit probability—

ProductCoturn

PublishedJul 10, 2026

First seenJul 10, 2026

Weakness typeCWE-918Server-side request forgery (SSRF)

How to fix

Update

coturn_project coturn4.13.0 or later

Affected products

Product	Affected versions	Fixed in
coturn_project coturn	v < 4.13.0	4.13.0

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