CVE-2026-53450: coturn_project coturn Server-Side Request Forgery (SSRF)

Vulnerability summary

CVE-2026-53450 is a high (CVSS 7.4) Server-Side Request Forgery (SSRF) vulnerability in coturn_project coturn. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 20.4% of scored vulnerabilities.

Timeline

1. 10-07-2026
   PublishedVulnerability first disclosed.
2. 10-07-2026
   Last modifiedVulnerability information updated.

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.

• CWE-918Server-Side Request Forgery (SSRF)The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.