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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.

PUBLISHED Reserved 2026-06-09 | Published 2026-07-10 | Updated 2026-07-10 | Assigner GitHub_M




HIGH: 7.4CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L

Problem types

CWE-918: Server-Side Request Forgery (SSRF)

Product status

< 4.13.0
affected

References

github.com/...coturn/security/advisories/GHSA-w4hf-cr3w-6h79 exploit

github.com/...coturn/security/advisories/GHSA-w4hf-cr3w-6h79

github.com/...ommit/b057acbebe721c8f2f202ddad5e16289e295c754

cve.org (CVE-2026-53450)

nvd.nist.gov (CVE-2026-53450)

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