CVE-2024-31966 is a vulnerability identified in several Mitel SIP phone models, including the 6800 and 6900 Series, 6900w Series, and the 6970 Conference Unit. The flaw arises from insufficient sanitization of input parameters in the device's administrative interface, which allows an authenticated attacker with administrative privileges to conduct an argument injection attack (CWE-88). This type of injection can manipulate command-line arguments or parameters passed to system functions, potentially enabling the attacker to execute arbitrary commands, alter system configurations, or access sensitive information stored on the device. The vulnerability affects firmware versions up to 6.3 SP3 HF4 for 6800/6900 Series, 6.3.3 for 6900w Series, and 5.1.1 SP8 for the 6970 Conference Unit. Exploitation requires administrative-level access, meaning the attacker must already have elevated privileges on the device, but does not require any user interaction. The CVSS v3.1 base score is 6.2, reflecting a medium severity level, with high impact on confidentiality, integrity, and availability, but limited by the requirement for privileged access and local network or management interface access. No public exploits have been reported yet, but the vulnerability poses a significant risk in environments where administrative credentials may be compromised or insufficiently protected. The root cause is improper input validation leading to argument injection, which can be leveraged to bypass security controls or escalate attacks within the telephony infrastructure.

The vulnerability could have serious consequences for organizations relying on Mitel SIP phones and conference units. Successful exploitation allows attackers to compromise the confidentiality of sensitive communications and configuration data, potentially exposing call logs, credentials, or network settings. Integrity is at risk as attackers can modify system configurations, potentially redirecting calls, disabling security features, or creating persistent backdoors. Availability may also be affected if arbitrary commands disrupt device operation or cause crashes. Given these devices often serve as critical communication endpoints in enterprise environments, disruption or compromise could impact business operations, customer service, and internal coordination. The requirement for administrative privileges limits the attack surface but also highlights the importance of protecting administrative accounts. Organizations with large deployments of Mitel telephony equipment, especially in sectors like finance, healthcare, government, and large enterprises, face increased risk. The lack of known exploits in the wild currently reduces immediate threat but does not eliminate the risk of future attacks, especially if attackers gain access to administrative credentials through phishing or insider threats.

1. Restrict administrative access to Mitel devices strictly to trusted personnel and secure management networks using network segmentation and VPNs. 2. Enforce strong, unique passwords and multi-factor authentication for all administrative accounts to reduce the risk of credential compromise. 3. Monitor administrative access logs and network traffic for unusual or unauthorized activity indicative of exploitation attempts. 4. Apply vendor firmware updates and patches promptly once Mitel releases fixes addressing this vulnerability. 5. Disable or limit remote administrative interfaces if not required, or restrict them to specific IP addresses. 6. Conduct regular security audits of telephony infrastructure to identify and remediate weak configurations or exposed management interfaces. 7. Educate administrators on the risks of argument injection and the importance of input validation in device management. 8. Consider deploying network-based intrusion detection/prevention systems (IDS/IPS) capable of detecting anomalous command injection patterns targeting SIP phones. These steps go beyond generic advice by focusing on administrative access controls, monitoring, and proactive patch management tailored to the telephony environment.