EXECUTIVE SUMMARY:
CVE-2026-20184 with a CVSS score of 9.8 is a critical vulnerability in Cisco Webex Services that allows an unauthenticated, remote attacker to impersonate any user within the service by exploiting a breakdown in improper certificate validation. The affected product is the integration between cloud-based Webex Services and the Cisco Control Hub, specifically impacted versions are not explicitly mentioned in the provided content. The vulnerability occurs due to flawed certificate validation logic, which enables an attacker to supply a crafted token to a service endpoint and have it accepted at face value without proper verification of the associated certificate's authenticity. An attacker can exploit this vulnerability by connecting to a service endpoint and supplying a crafted token, requiring only remote access. A successful exploit grants the attacker the capability to impersonate any user within the service, enabling them to access sensitive meetings, data exfiltration, and lateral movement within the platform. If exploited, the business impact could lead to unauthorized access to confidential information, data breaches, and potential loss of credibility. Prerequisites for exploitation are not explicitly mentioned in the provided content.[/subscribe_to_unlock_form]
EXECUTIVE SUMMARY:
CVE-2026-20184 with a CVSS score of 9.8 is a critical vulnerability in Cisco Webex Services that allows an unauthenticated, remote attacker to impersonate any user within the service by exploiting a breakdown in improper certificate validation. The affected product is the integration between cloud-based Webex Services and the Cisco Control Hub, specifically impacted versions are not explicitly mentioned in the provided content. The vulnerability occurs due to flawed certificate validation logic, which enables an attacker to supply a crafted token to a service endpoint and have it accepted at face value without proper verification of the associated certificate's authenticity. An attacker can exploit this vulnerability by connecting to a service endpoint and supplying a crafted token, requiring only remote access. A successful exploit grants the attacker the capability to impersonate any user within the service, enabling them to access sensitive meetings, data exfiltration, and lateral movement within the platform. If exploited, the business impact could lead to unauthorized access to confidential information, data breaches, and potential loss of credibility. Prerequisites for exploitation are not explicitly mentioned in the provided content.[emaillocker id="1283"]
RECOMMENDATION:
We recommend you update Cisco Webex Services to version 40.12 or later.
We recommend you update Control Hub to version 31.12 or later.
REFERENCES:
The following reports contain further technical details:
https://securityonline.info/cisco-webex-sso-vulnerability-cve-2026-20184-impersonation-fix/