CVE-2026-53450: coturn SSRF — Fix

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.

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CVSS v3.1 Score

7.4

HIGH

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

EPSS — Exploit Prediction

0.0029

Probability of exploitation

0.21%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-918 Server-Side Request Forgery (SSRF)

Affected Products

Vendor	Product	Versions
coturn_project	coturn	< 4.13.0

References

Advisories & Patches

https://github.com/coturn/coturn/commit/b057acbebe721c8f2f202ddad5e16289e295c754

Other References

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

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 7.4 (HIGH).

How severe is CVE-2026-53450? +

CVE-2026-53450 has a CVSS v3.1 score of 7.4 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0029, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-53450? +

CVE-2026-53450 affects products from coturn_project, specifically: coturn. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-53450? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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