# CVE-2026-68553

## Summary

- **CVE ID:** CVE-2026-68553
- **Severity:** HIGH
- **CVSS Score:** 7.1 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H)
- **CWE:** CWE-134
- **Published:** Aug 19, 2026
- **Last Modified:** Aug 20, 2026

## 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.

## Affected Products

- coturn — coturn (< 4.13.0)

## References

- [CNA](https://github.com/coturn/coturn/security/advisories/GHSA-4g7c-p5wg-j4hp)
- [CNA](https://github.com/coturn/coturn/commit/8fa38032bb4751e11e072d65a8eca3c06c950979)
- [CNA](https://github.com/coturn/coturn/releases/tag/4.13.0)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.28%
- **EPSS Percentile:** 20.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._