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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-68553
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-19 21:17:28 UTC
Updated2026-08-20 20:17:45 UTC
DescriptionCoturn 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.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H

EPSS: 0.002790000 probability, percentile 0.204760000 (date 2026-08-21)

Problem Types: CWE-134 | CWE-134 CWE-134: Use of Externally-Controlled Format String

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H
3.1CNADECLARED7.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Coturn Coturn affected < 4.13.0 Not specified

References

ReferenceSourceLinkTags
github.com/coturn/coturn/releases/tag/4.13.0 [email protected] github.com
github.com/coturn/coturn/security/advisories/GHSA-4g7c-p5wg-j4hp 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/coturn/coturn/commit/8fa38032bb4751e11e072d65a8eca3c06c950979 [email protected] github.com
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