CVE-2026-68553Network attack vector

Authenticated crash or stack disclosure via Redis format

Published Aug 19, 2026 · Updated Aug 20, 2026

Format string injection in coturn before 4.13.0 allows remote authenticated users to crash the server via crafted STUN USERNAME or REALM values. is_secure_string() in src/apps/common/ns_turn_utils.c accepts '%' characters, src/apps/relay/ns_ioalib_engine_impl.c copies the resulting USERNAME or REALM into Redis keys, and send_message_to_redis() in src/apps/relay/hiredis_libevent2.c passes that key to redisAsyncCommand() as the format string while supplying only one data argument. Reachability is limited to deployments with hiredis integration and valid TURN credentials; exploitation can terminate active TURN sessions and can write stack-derived data into Redis, but the public record does not show a reliable integrity impact.

CVSS severity7.1
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Format string injection in coturn before 4.13.0 allows remote authenticated users to crash the server via crafted STUN USERNAME or REALM values. is_secure_string() in src/apps/common/ns_turn_utils.c accepts '%' characters, src/apps/relay/ns_ioalib_engine_impl.c copies the resulting USERNAME or REALM into Redis keys, and send_message_to_redis() in src/apps/relay/hiredis_libevent2.c passes that key to redisAsyncCommand() as the format string while supplying only one data argument. Reachability is limited to deployments with hiredis integration and valid TURN credentials; exploitation can terminate active TURN sessions and can write stack-derived data into Redis, but the public record does not show a reliable integrity impact.

The record

CVE
CVE-2026-68553
Published
Aug 19, 2026
Updated
Aug 20, 2026
Vendor
coturn
Product
coturn
Classifications
CWE-134, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.13.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

coturn · coturnversion=< 4.13.0

Published CVSS scores

7.1GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-134Use of Externally-Controlled Format String
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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