Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.13.1, good_peer_addr() in src/server/ns_turn_server.c uses ioa_addr_in_range() in src/client/ns_turn_ioaddr.c without canonicalizing IPv4-compatible, 6to4, and 64:ff9b::/96 NAT64 address forms, allowing an authenticated RFC 6062 TCP CONNECT relay client to bypass an IPv4 denied-peer-ip range when the Coturn host has a useful translation route. This issue is fixed in version 4.13.1.
https://github.com/coturn/coturn/security/advisories/GHSA-2x4g-wx24-48m4
https://github.com/coturn/coturn/releases/tag/4.13.1
https://github.com/coturn/coturn/pull/1947
https://github.com/coturn/coturn/pull/1945
https://github.com/coturn/coturn/commit/d49ee56aa9fe748af064853d5e430eec1ccc3cbc
https://github.com/coturn/coturn/commit/cf4b4952de48510d38415b96300da5fc674bfdda
Published: 2026-08-11
Updated: 2026-08-11
Base Score: 4
Vector: CVSS2#AV:N/AC:L/Au:S/C:N/I:P/A:N
Severity: Medium
Base Score: 7.5
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Severity: High
Base Score: 5.8
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H
Severity: Medium