Customers using Cisco Unified Communications should patch the high-severity vulnerability or mitigate its risks

Cisco has taken immediate action in response to the discovery of a critical remote code execution vulnerability, known as CVE-2024-20253, within its Unified Communications Systems. This vulnerability, with a CVSS score of 9.9, poses a significant threat to enterprise communications infrastructure and customer service call centers. It exposes them to potential attacks from unauthenticated remote adversaries.

The vulnerability, stemming from the mishandling of user-provided data, can lead to memory corruption. Exploiting this flaw, remote attackers can send crafted messages to vulnerable devices’ listening ports, enabling them to execute arbitrary code on the underlying operating system. This could grant attackers the privileges of the web services user or even gain root access to the compromised device.

The implications of CVE-2024-20253 go beyond system compromise. Organizations relying on Cisco’s Unified Communications and Contact Center Solutions face severe consequences. Attackers could disrupt operations, compromise sensitive data, eavesdrop on communications, or launch additional attacks such as ransomware or data exfiltration attempts.

Recognizing the seriousness of this vulnerability, Cisco has promptly issued a security advisory. This advisory provides comprehensive details on affected product versions and offers patches to effectively address the vulnerability. It is crucial for organizations to implement these mitigation measures to safeguard their communication services and protect against potential attacks.

For users who are unable to immediately apply updates, Cisco recommends implementing access control lists (ACLs) on intermediary devices. These ACLs serve as a barrier between the UC/CC cluster and the wider network, limiting access to only the necessary ports for deployed services. While this offers temporary relief, it emphasizes the urgency of patching affected systems.


CVE-2024-20253 serves as a stark reminder of the ever-changing threat landscape that modern communication systems face. Through collaboration between vendors and users, proactive identification, mitigation, and resolution of vulnerabilities are vital in maintaining a secure digital ecosystem. Cisco’s response underscores the significance of taking prompt action and maintaining constant vigilance in the face of emerging cybersecurity challenges.