SB2026080336 - Multiple vulnerabilities in coTURN
Published: August 3, 2026 Updated: August 5, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 4 vulnerabilities.
1) Resource exhaustion (CVE-ID: CVE-2026-68555)
CWE-ID: CWE-400 - Resource exhaustion
CVSSv4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in the mobility resume transition handling in src/server/ns_turn_server.c when processing chained authenticated mobility resume requests. A remote user can repeatedly resume one allocation from new UDP 5-tuples without completing the handoff to cause a denial of service.
Only deployments with the --mobility feature enabled are affected, and the issue can persist even when the allocation quota is set to one.
2) Allocation of Resources Without Limits or Throttling (CVE-ID: N/A)
CWE-ID: CWE-770 - Allocation of Resources Without Limits or Throttling
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to allocation of resources without limits or throttling in the DTLS listener session handling in src/apps/relay/dtls_listener.c when processing initial fragmented ClientHello messages before DTLS cookie validation. A remote attacker can send specially crafted UDP datagrams from fresh source tuples to cause a denial of service.
DTLS must be enabled with a certificate and private key. No TURN credential, completed handshake, valid cookie, source-address spoofing, or response processing is required, and a single host can vary its UDP source port to create distinct tuples.
3) Allocation of Resources Without Limits or Throttling (CVE-ID: N/A)
CWE-ID: CWE-770 - Allocation of Resources Without Limits or Throttling
CVSSv4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to allocation of resources without limits or throttling in the multiplex-peer demux table when processing SEND indications, CreatePermission, or ChannelBind requests with attacker-chosen XOR-PEER-ADDRESS values in multiplex-peer mode. A remote user can send specially crafted requests with many distinct peer IP:port combinations to cause a denial of service.
The issue is exposed when the server is started with --multiplex-peer. A single permitted peer IP can be expanded across many ports, and the shared per-worker-thread table is fully scanned during permission expiry and session teardown, which increases CPU consumption for other sessions on the same worker.
4) Incorrect authorization (CVE-ID: N/A)
CWE-ID: CWE-863 - Incorrect Authorization
CVSSv4: 2.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to bypass IPv6 peer address restrictions and reach an intended-denied service through TURN relaying.
The vulnerability exists due to incorrect authorization in addr_less_eq() in src/client/ns_turn_ioaddr.c when evaluating non-prefix-aligned IPv6 min-max peer ranges. A remote user can send CONNECT and CONNECTION-BIND requests for a crafted IPv6 peer address to bypass IPv6 peer address restrictions and reach an intended-denied service through TURN relaying.
Exploitation requires a custom non-prefix-aligned IPv6 min-max rule and a reachable peer service from the Coturn server. Exact-address and ordinary prefix-aligned controls are not affected in the same way.
Remediation
Install update from vendor's website.