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CVE-2026-43915 coturn CVE debrief

Coturn, a free open-source implementation of TURN and STUN Server, has a stored cross-site scripting (XSS) vulnerability in its web-admin HTTPS interface. An attacker can create a TURN allocation with a crafted USERNAME value to inject HTML/JavaScript that executes when an authenticated web-admin user views the TURN session list. This issue may be exploitable without TURN credentials in configurations using anonymous TURN access. In authenticated deployments, valid TURN credentials or control over a provisioned username are required for exploitation. The vulnerability has been fixed in version 4.11.0.

Vendor
coturn
Product
Unknown
CVSS
MEDIUM 5.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-18
Original CVE updated
2026-06-26
Advisory published
2026-06-18
Advisory updated
2026-06-26

Who should care

Administrators and users of Coturn TURN and STUN Server, especially those using versions prior to 4.11.0, should be aware of this vulnerability. This includes organizations that rely on Coturn for real-time communication services, as an attacker could potentially inject malicious scripts into the web-admin interface.

Technical summary

The vulnerability exists in the web-admin HTTPS interface of Coturn versions prior to 4.11.0. An attacker can exploit this by creating a TURN allocation with a specially crafted USERNAME value. When an authenticated web-admin user views the TURN session list, the injected HTML/JavaScript will execute. The CVSS score for this vulnerability is 5.4, indicating a medium severity. The vulnerability is classified under CWE-79, which covers cross-site scripting (XSS) attacks.

Defensive priority

MEDIUM

Recommended defensive actions

  • Update Coturn to version 4.11.0 or later to fix the vulnerability.
  • Implement proper input validation and sanitization for USERNAME values in TURN allocations.
  • Use secure authentication mechanisms for web-admin access.
  • Monitor web-admin interface for suspicious activity.
  • Restrict access to the web-admin interface to trusted users and networks.
  • Regularly review and update Coturn configurations to ensure secure settings.

Evidence notes

The information provided is based on the CVE record and NVD details for CVE-2026-43915. The vulnerability was published on June 18, 2026, and last modified on the same day. The CVSS score and vector are based on the NVD's assessment.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-43915 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-43915

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-43915 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-43915

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.