CVE-2025-20236 is a critical vulnerability discovered in Cisco Webex Teams, specifically in the custom URL parser component responsible for handling meeting invite links. The root cause is insufficient input validation, allowing an attacker to craft malicious meeting invite URLs that trigger the download of arbitrary files onto the victim's system. When a user clicks such a link, the application processes the URL without properly sanitizing input, leading to the execution of arbitrary commands with the same privileges as the user running the Webex Teams client. This flaw enables remote, unauthenticated attackers to compromise user systems by social engineering users into clicking malicious links. The vulnerability affects multiple versions of Cisco Webex Teams, including 44.6, 44.6.0.29928, 44.6.0.30148, 44.7, 44.7.0.30141, and 44.7.0.30285. The CVSS 3.1 base score is 8.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity, no privileges required, but user interaction necessary. Although no active exploits have been reported, the vulnerability poses a significant risk due to the widespread use of Cisco Webex Teams in enterprise environments for communication and collaboration. The attacker’s ability to execute arbitrary commands could lead to data theft, lateral movement, or deployment of malware within corporate networks.

The vulnerability allows attackers to execute arbitrary commands on the victim's machine with user-level privileges, potentially leading to full compromise of the user's environment. This can result in unauthorized access to sensitive corporate data, installation of persistent malware, lateral movement within networks, and disruption of business operations. Given Cisco Webex Teams' extensive deployment in enterprises worldwide, exploitation could affect a large number of organizations, especially those relying heavily on Webex for communication. The attack requires user interaction but no authentication, increasing the risk of successful phishing campaigns. The high CVSS score indicates severe impact on confidentiality, integrity, and availability, making this a critical threat to organizational security.

Organizations should immediately verify the versions of Cisco Webex Teams deployed and prioritize upgrading to patched versions once Cisco releases them. Until patches are available, implement network-level controls to block or monitor suspicious meeting invite URLs, especially those originating from untrusted sources. Educate users to be cautious about clicking meeting invite links received via email or messaging, particularly from unknown or unexpected senders. Employ endpoint protection solutions capable of detecting and blocking execution of unauthorized files or commands spawned by Webex Teams. Consider application whitelisting and restricting execution privileges for Webex Teams processes where feasible. Monitor logs and network traffic for anomalous activities related to Webex Teams usage. Finally, maintain robust incident response plans to quickly address any suspected exploitation.