coturn TURN Unsafe Loopback Forwarding Unauthorized Access Vulnerability [CVE-2018-4058]

CVE Number – CVE-2018-4058

A vulnerability in the coturn Traversal Using Relay NAT (TURN) server functionality could allow an authenticated, remote attacker to gain unauthorized access to sensitive information on a targeted system.The vulnerability is due to an unsafe default configuration that allows the affected software to enable loopback forwarding to relay external traffic to the loopback interface. An attacker could exploit this vulnerability by setting up a relay with a loopback address as the peer on a targeted TURN server that is designed to forward traffic from an external interface to the server loopback. An exploit could allow the attacker to gain unauthorized access to other sensitive services running on the loopback interface.The coturn TURN server project has confirmed the vulnerability and released software updates.


  • To exploit this vulnerability, the attacker must have user-level access to the targeted system. This requirement could reduce the likelihood of a successful exploit.Cisco Talos has released a vulnerability report at the following link: TALOS-2018-0732


  • Administrators are advised to apply the appropriate updates.Administrators are advised to allow only trusted users to have network access.Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.Administrators can help protect affected systems from external attacks by using a solid firewall strategy.Administrators are advised to monitor affected systems.

Vendor Announcements

Fixed Software

  • The coturn TURN server project has released software updates at the following link: coturn

Duncan Newell

Duncan is a technology professional with over 20 years experience of working in various IT roles. He has a interest in cyber security, and has a wide range of other skills in radio, electronics and telecommunications.

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