CVE-2026-68555: Coturn

Medium severity, CVSS 6.5. EPSS: 0.5% chance of exploitation in the next 30 days.

Coturn is a free open source implementation of TURN and STUN Server. In 4.15.0, an authenticated TURN user can repeatedly resume one allocation from fresh UDP 5-tuples without completing a handoff when the server enables --mobility. mobile_begin_transition() in src/server/ns_turn_server.c disarms each new session's allocation timeout and overwrites the allocation's single mobile_pending_resume link, leaving earlier pending sessions unreachable by the cleanup path, while copy_auth_parameters() ignores inc_quota() failure. The attacker can therefore retain unbounded server-side sessions and exhaust process memory even when --user-quota=1 is configured. This issue is fixed in version 4.16.0.

Affected products

• Coturn Coturn: from 4.15.0, before 4.16.0 (fixed in 4.16.0)

Published 2026-08-19. Last modified 2026-09-09.