Coturn: STUN attributes after MESSAGE-INTEGRITY are processed, letting on-path attackers modify authenticated TURN requests

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-68554
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-19 21:17:28 UTC
Updated2026-08-20 14:17:52 UTC
DescriptionCoturn is a free open source implementation of TURN and STUN Server. Prior to 4.15.0, an on-path attacker can append attributes after MESSAGE-INTEGRITY to an authenticated STUN request on plain UDP or TCP, adjust the STUN header length, and recompute the unkeyed FINGERPRINT while the original HMAC remains valid because it covers only the message prefix. Server-side parsing in src/server/ns_turn_server.c continues past MESSAGE-INTEGRITY through handle_turn_allocate(), handle_turn_create_permission(), handle_turn_refresh(), and handle_turn_command(), allowing trailing LIFETIME, XOR-PEER-ADDRESS, or ORIGIN attributes to override allocation lifetime, inject a permission, or bypass the origin check. TLS and DTLS deployments prevent this in-transit modification. This issue is fixed in version 4.15.0.

Risk And Classification

Primary CVSS: v4.0 2.3 LOW from [email protected]

CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.001310000 probability, percentile 0.031190000 (date 2026-08-20)

Problem Types: CWE-345 | CWE-924 | CWE-345 CWE-345: Insufficient Verification of Data Authenticity | CWE-924 CWE-924: Improper Enforcement of Message Integrity During Transmission in a Communication Channel

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary2.3LOWCVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/C...
4.0CNADECLARED2.3LOWCVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
Low
Availability
Low
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Coturn Coturn affected < 4.15.0 Not specified

References

ReferenceSourceLinkTags
github.com/coturn/coturn/security/advisories/GHSA-5538-7cxj-5jcc 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/coturn/coturn/commit/ab762f334f511ea37ab4b703a47d5d683a5be978 [email protected] github.com
github.com/coturn/coturn/releases/tag/4.15.0 [email protected] github.com
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