CVE-2026-68553

Coturn: Format String Injection via TURN USERNAME/REALM into hiredis Redis Command

Published: Aug 19, 2026Updated: Sep 9, 2026 Sources: CVE List NVDCWE-134

7.1HIGH

Description

Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.13.0, an authenticated TURN user can place printf-style format specifiers in the STUN USERNAME or REALM attribute, which passes is_secure_string() validation and is embedded into Redis keys at nine call sites in src/apps/relay/ns_ioalib_engine_impl.c. send_message_to_redis() in src/apps/relay/hiredis_libevent2.c then passes the attacker-controlled key as the format argument to redisAsyncCommand() while supplying only one variadic value, causing hiredis redisvFormatCommand() to read past the va_list. Exploitation can crash the coturn process and terminate active TURN sessions or disclose stack memory into Redis. This issue is fixed in version 4.13.0.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:LPrivileges Required

Low

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:LConfidentiality

Low

I:NIntegrity

None

A:HAvailability

High

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Weaknesses

CWE-134

Affected Products

coturn

oss-project

coturnOn-prem

Networking Infrastructure / load-balancer-proxy

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique

Execution

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References

https://github.com/coturn/coturn/security/advisories/GHSA-4g7c-p5wg-j4hp

github.com

https://github.com/coturn/coturn/commit/8fa38032bb4751e11e072d65a8eca3c06c950979

github.com

https://github.com/coturn/coturn/releases/tag/4.13.0

github.com

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