Coturn: STUN attributes after MESSAGE-INTEGRITY are processed, letting on-path attackers modify authenticated TURN requests
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.
- Published
- Aug 19, 2026
- Updated
- Sep 9, 2026
- EPSS
- 0.2% · 8th percentile
- CWE
- CWE-345
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Report tools
Action score
9
Monitor
Low priority for now.
- CVSS
- 9 / 40 · 2.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · GitHub_M
- 2.3
- NVD has not scored this yet; the score shown is the CNA’s.
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
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
coturn coturn
- < 4.15.0affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | coturn | all versions | — |
| openSUSE:Tumbleweed | coturn | before 4.17.2-1.1 | 4.17.2-1.1 |
Same product
coturn: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-73214coturn allocates a full per-peer SSL/session before verifying the DTLS cookie, enabling source-spoofing/botnet state-exhaustion DoS32Monitor
- CVE-2026-62959Coturn: Pre-authentication heap memory disclosure in ACME redirect (`try_acme_redirect`)32Monitor
- CVE-2025-69217Coturn has unsafe nonce and relay port randomization due to weak random number generation.30Monitor
- CVE-2026-68553Coturn: Format String Injection via TURN USERNAME/REALM into hiredis Redis Command28Monitor
- CVE-2026-73215The coturn server can end in a state where it does not accept more requests with "even-port" enabled.28Monitor
- CVE-2026-65981Coturn: MOBILITY-TICKET session-resume authorization bypass allows cross-user TURN allocation takeover28Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| coturn coturn | 4.15.0 · description | Vendor (CNA) |
| opensuse:coturn | 4.17.2-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone on the same network segment can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Adjacent
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- X
Weakness class (CWE)
CWE-345 · Insufficient Verification of Data AuthenticityCVSS vector
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
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- JSON Hijacking (aka JavaScript Hijacking)CAPEC-111likelihood: High · High
- Cache PoisoningCAPEC-141likelihood: High · High
- DNS Cache PoisoningCAPEC-142likelihood: High · High
- Content SpoofingCAPEC-148likelihood: Medium · Medium
- Spoofing of UDDI/ebXML MessagesCAPEC-218Medium
- Application API Message Manipulation via Man-in-the-MiddleCAPEC-384Low
- Transaction or Event Tampering via Application API ManipulationCAPEC-385Medium
- Application API Navigation RemappingCAPEC-386Medium
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/coturn/coturn/commit/ab762f334f511ea37ab4b703a47d5d683a5be978
- github.com/coturn/coturn/releases/tag/4.15.0
- github.com/coturn/coturn/security/advisories/GHSA-5538-7cxj-5jcc
Vendor advisories and official records. Exploit/PoC links are deliberately left out.