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Public proof of conceptFix available

CVE-2026-68553

A public proof of concept exists; no exploitation attested.

  • Published2026-08-19
  • WeaknessCWE-134

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-08-1921:17CVE publishedNVD

Versions per branch

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • coturnUbuntu:26.10all versions · no fixed version listed
  • coturnUbuntu:26.04:LTSall versions · no fixed version listed
  • coturnUbuntu:24.04:LTSall versions · no fixed version listed
  • coturnUbuntu:22.04:LTSall versions · no fixed version listed
  • coturnUbuntu:20.04:LTSall versions · no fixed version listed
  • coturnUbuntu:18.04:LTSall versions · no fixed version listed
  • coturnUbuntu:16.04:LTSall versions · no fixed version listed
  • coturnopenSUSE:Tumbleweedall versions · fixed in 4.17.2-1.1

3 more package ranges on OSV.dev

Vendor advisories

  • CVE-2026-68553 Red Hat Product Security

    coturn: Coturn: Format string vulnerability leads to denial of service and information disclosure

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • NVDCVE recordread 2026-10-26
  • CISA-ADPSSVC decisionpoc2026-08-20
  • CNACVSS 3.17.1known since 2026-10-26
  • CNAweakness (CWE)CWE-134known since 2026-10-26
  • FIRST EPSSEPSS score0.5 %2026-11-08
  • OSVaffected packages—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H
Published
2026-08-19
Last Modified
2026-10-26
NVD status
Deferred

Frequently asked questions

What is CVE-2026-68553?

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.

Is CVE-2026-68553 actively exploited?

A proof-of-concept exploit exists for CVE-2026-68553, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-68553?

CVE-2026-68553 has a CVSS v3 base score of 7.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H.

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Sources for this record