CVE-2026-73216: coturn: mobility disconnects bypass allocation quotas and exhaust relay capacity

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-11 · updated 2026-09-09
Weakness: CWE-400

Description

Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.17.0, shutdown_client_connection() in src/server/ns_turn_server.c prematurely calls dec_quota() and releases bandwidth accounting during the first-stage close of a mobility-enabled allocation while preserving the allocation, relay socket, session, and mobility ticket, allowing an authenticated client to bypass --user-quota and --total-quota and exhaust relay ports. This issue is fixed in version 4.17.0.

Affected products

coturn: before 4.17.0

References

https://github.com/coturn/coturn/commit/3c5b2615fd405c4e7c5bf3fbeef895c94a90671b
https://github.com/coturn/coturn/releases/tag/4.17.0
https://github.com/coturn/coturn/security/advisories/GHSA-f6hc-79w3-p8pq

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