SSRF in Coturn
CVE-2026-53450
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.
Vulnerability class: SSRF (Server-Side Request Forgery)
EPSS: 0.003 (21.0th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L.
Affected products
- Coturn — versions < 4.13.0
- Coturn_project Coturn
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-53450?
- CVE-2026-53450 is a high-severity vulnerability in Coturn, classified under Server-Side Request Forgery (SSRF). CVSS score: 7.4/10. Published 2026-07-10.
- How severe is CVE-2026-53450?
- High severity. CVSS v3 base score is 7.4 out of 10.