Coturn: Prior to 4.17.0, shutdown_client_connection() in src/server/ns_turn_server.c prematurely calls dec_quota() and releases bandwidth accounting during… (CVE-2026-73216)
Description
Coturn versions prior to 4.17.0 contain a vulnerability in the shutdown_client_connection() function where bandwidth accounting is prematurely released during the first-stage close of a mobility-enabled allocation. This allows an authenticated client to bypass user and total quota limits and potentially exhaust relay ports. The issue is addressed in version 4.17.0.
CVSS v3.1
Score 6.5medium
Affected software
pkg:deb/ubuntu/coturn?arch=source&distro=xenialpkg:deb/ubuntu/coturn?arch=source&distro=bionicpkg:deb/ubuntu/coturn?arch=source&distro=focalpkg:deb/ubuntu/coturn?arch=source&distro=jammypkg:deb/ubuntu/coturn?arch=source&distro=noblepkg:deb/ubuntu/coturn?arch=source&distro=stonkingpkg:deb/ubuntu/coturn?arch=source&distro=resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Coturn, an open source TURN and STUN server, has a vulnerability identified as CVE-2026-73216 affecting versions prior to 4.17.0. The function shutdown_client_connection() in src/server/ns_turn_server.c prematurely calls dec_quota(), releasing bandwidth accounting during the initial close phase of a mobility-enabled allocation while still preserving the allocation, relay socket, session, and mobility ticket. This flaw enables an authenticated client to bypass the --user-quota and --total-quota restrictions, potentially exhausting relay ports. The vulnerability has a CVSS 3.1 score of 6.5 (medium severity) with network attack vector, low attack complexity, requiring low privileges, no user interaction, unchanged scope, no confidentiality or integrity impact, but high availability impact. The issue is fixed in Coturn version 4.17.0.
Potential Impact
Authenticated clients can bypass bandwidth quota restrictions (--user-quota and --total-quota) due to premature quota decrementing, which may lead to exhaustion of relay ports and denial of service by impacting availability of the TURN server resources.
Mitigation Recommendations
Upgrade Coturn to version 4.17.0 or later, where this issue is fixed. No other mitigations are specified or recommended by the vendor. Patch status is confirmed as fixed in 4.17.0.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-73216
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:16.04:LTS","Ubuntu:18.04:LTS","Ubuntu:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:26.10","Ubuntu:26.04:LTS"]
- Cvss Version
- 3.1
Threat ID: 6ad3f58b2cdf04f6566621be
Added to database: 10/17/2026, 22:24:11 UTC
Last enriched: 10/17/2026, 23:47:39 UTC
Last updated: 10/17/2026, 23:47:39 UTC
Views: 3
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