CVE-2026-73215
HighCVSS 7.1Exploitation Probability (EPSS)
Low risk26th percentile - higher than 26% of all known CVEs
Summary
Coturn before version 4.17.0 has a vulnerability in turnports_allocate_even() that marks the unused odd sibling port as TPS_TAKEN_ODD for an EVEN-PORT Allocate request with reservation bit R=0 even though no RTCP socket will release it. An authenticated client can permanently exhaust the relay port pool, causing subsequent allocations to fail with STUN error 508.
Risk Assessment
The attack can lead to exhaustion of the relay port pool, preventing new clients from using the TURN server, causing service disruptions.
Recommendation
Update Coturn to version 4.17.0 or later and monitor relay port usage for anomalies.
Original NVD description (English source)
Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.17.0, turnports_allocate_even() in src/apps/relay/turn_ports.c marks the unused odd sibling port as TPS_TAKEN_ODD for an EVEN-PORT Allocate request with reservation bit R=0 even though no RTCP socket will release it, allowing an authenticated client to permanently exhaust the relay port pool and cause subsequent allocations to fail with STUN error 508. This issue is fixed in version 4.17.0.