Coturn: STUN attributes after MESSAGE-INTEGRITY are processed, letting on-path attackers modify authenticated TURN requests
Published Aug 19, 2026
2.3
LOWCVSS 4.0
EPSS 0.19%
Description
Coturn 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.
Affected products
-
- Version < 4.15.0StatusaffectedConstraints-
- Version
No data.
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
Red Hat statement
Coturn is not shipped in any Red Hat product. The Fedora and EPEL community builds ship coturn version 4.17.2, which already includes the fix for this issue (fixed in 4.15.0) and are therefore not affected.
Red Hat mitigation
Upgrade to coturn version 4.15.0 or later. Deployments using TLS or DTLS transports are not vulnerable to this issue.
Metrics
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
1 other source (NVD) ▾
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
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
PoCAutomatable
NoTechnical Impact
PartialDecision
n/aAssessed Aug 20, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 3, 2026.
Score over time
Aug–Oct 2026- EPSS v5
Percentile over time
- EPSS v5
Table of values (2 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 3, 2026 | 0.19% (0.00188) | 7.60th | v5 (v2026.06.15) |
| Aug 20, 2026 | 0.13% (0.00131) | 3.12th | v5 (v2026.06.15) |
References (7)
- https://access.redhat.com/security/cve/CVE-2026-68554 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2520325 Issue Tracking
- https://github.com/coturn/coturn/commit/ab762f334f511ea37ab4b703a47d5d683a5be978 x_refsource_MISC
- https://github.com/coturn/coturn/releases/tag/4.15.0 x_refsource_MISC
- https://github.com/coturn/coturn/security/advisories/GHSA-5538-7cxj-5jcc exploitx_refsource_CONFIRM
- https://nvd.nist.gov/vuln/detail/CVE-2026-68554
- https://www.cve.org/CVERecord?id=CVE-2026-68554
| Link | Providers | Tags |
|---|---|---|
| https://access.redhat.com/security/cve/CVE-2026-68554 | Vendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=2520325 | Issue Tracking | |
| https://github.com/coturn/coturn/commit/ab762f334f511ea37ab4b703a47d5d683a5be978 | x_refsource_MISC | |
| https://github.com/coturn/coturn/releases/tag/4.15.0 | x_refsource_MISC | |
| https://github.com/coturn/coturn/security/advisories/GHSA-5538-7cxj-5jcc | exploitx_refsource_CONFIRM | |
| https://nvd.nist.gov/vuln/detail/CVE-2026-68554 | ||
| https://www.cve.org/CVERecord?id=CVE-2026-68554 |
Change history (0)
No recorded changes yet.