CVE-2026-53450CWE-918

Coturn: IPv4-mapped 127.0.0.1 bypasses default loopback peer protection

High · published July 10, 2026

CVSS v3.1
7.4
EPSS
0%
Percentile
20.4
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.4 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L
CVSS v4.0
Not supplied
EPSS
0.00290 · 20.4th percentile
Weakness
CWE-918 · Server-Side Request Forgery (SSRF)
Published
2026-07-10T18:05Z
EPSS history
Timeline
  • 10 JUL 18:05Z
    Coturn: IPv4-mapped 127.0.0.1 bypasses default loopback peer protection
    cvelistv5