CVE-2024-31964 is a vulnerability identified in Mitel 6800 Series and 6900 Series SIP Phones through firmware version 6.3 SP3 HF4, the 6900w Series SIP Phone through 6.3.3, and the 6970 Conference Unit through 5.1.1 SP8. The root cause is improper authentication control (CWE-284), which allows an unauthenticated attacker to bypass authentication mechanisms. This bypass enables the attacker to access administrative functions without credentials, potentially modifying system configuration settings. Such unauthorized changes could disrupt normal device operation or cause denial of service (DoS). The vulnerability is remotely exploitable over the network without requiring any privileges or user interaction, increasing its risk profile. Although no public exploits have been reported yet, the CVSS v3.1 base score of 7.5 (high) reflects the significant impact on availability and ease of exploitation. The affected devices are commonly deployed in enterprise telephony environments, making them attractive targets for attackers seeking to disrupt communications or gain footholds in corporate networks. The lack of available patches at the time of reporting necessitates immediate mitigation through network segmentation and access controls.

The primary impact of CVE-2024-31964 is on the availability and integrity of affected Mitel SIP phones and conference units. An attacker exploiting this vulnerability can bypass authentication controls to alter system configurations, potentially causing device malfunctions or denial of service. This can disrupt voice communications critical to business operations, leading to operational downtime and loss of productivity. Additionally, unauthorized configuration changes might be leveraged to facilitate further attacks, such as intercepting calls or pivoting within the network. Organizations relying heavily on these Mitel devices for unified communications face increased risk of targeted attacks, especially in sectors where telephony infrastructure is vital, such as finance, healthcare, and government. The ease of remote exploitation without authentication or user interaction broadens the attack surface and increases the likelihood of exploitation if mitigations are not applied promptly.

1. Immediately restrict network access to affected Mitel devices by implementing strict firewall rules and network segmentation to limit exposure to untrusted networks. 2. Monitor vendor communications closely for official patches or firmware updates addressing this vulnerability and apply them as soon as they become available. 3. Disable remote management interfaces if not required or restrict them to trusted IP addresses only. 4. Conduct regular audits of device configurations and logs to detect unauthorized changes or suspicious activity. 5. Employ network intrusion detection systems (NIDS) to identify anomalous traffic patterns targeting SIP phones. 6. Educate IT and security teams about this vulnerability to ensure rapid response and incident handling. 7. Consider deploying additional authentication mechanisms or VPN tunnels for remote device management to add layers of security beyond the vulnerable authentication controls.