High7.4Red Hat Linux

High [CVE-2026-53450] Localhost services exposed via IPv4-mapped IPv6 address bypass

This high-severity Red Hat Linux advisory covers CVE-2026-53450.

CVE-2026-53450 Published Jul 10, 2026Updated by vendor Jul 10, 2026

CVE-2026-53450

Affected products & platforms

Red Hat LinuxUnclassified

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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-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. This could lead to unauthorized access to internal services.

This flaw affects the community-maintained coturn TURN/STUN server as shipped in Fedora and EPEL. Red Hat does not ship coturn in any core Red Hat product.

Fedora and EPEL currently ship coturn 4.14.0, which already includes the fix released in 4.13.0, so the shipped builds are not vulnerable to this loopback-protection bypass via IPv4-mapped IPv6 addresses. Red Hat severity: Important — CVSS 7.4 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L).

Weakness: CWE-289.

Affected versions

< 4.13.0
< 127.0.0.1

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

Fixed versions

4.13.0

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation

No action needed — the shipped coturn build (4.14.0) already contains the upstream fix.

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

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