High severity · published Jul 10, 2026
CVE-2026-53450
Coturn: IPv4-mapped 127.0.0.1 bypasses default loopback peer protection
7.4
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
Low
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 21% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CO
coturn · coturn
< 4.13.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-53450
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-53450
Patch
https://github.com/coturn/coturn/commit/b057acbebe721c8f2f202ddad5e16289e295c754
Third Party Advisory
https://github.com/coturn/coturn/security/advisories/GHSA-w4hf-cr3w-6h79
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