CVE-2021-22006 in vCenter Server
Summary
by MITRE • 09/24/2021
The vCenter Server contains a reverse proxy bypass vulnerability due to the way the endpoints handle the URI. A malicious actor with network access to port 443 on vCenter Server may exploit this issue to access restricted endpoints.
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Analysis
by VulDB Data Team • 10/01/2021
The vulnerability identified as CVE-2021-22006 represents a critical reverse proxy bypass flaw within VMware vCenter Server implementations that directly compromises the security posture of virtualized environments. This issue stems from improper handling of URI parameters within the server's endpoint processing mechanisms, creating a pathway for unauthorized access to protected administrative functions. The vulnerability specifically affects the reverse proxy configuration that governs how incoming requests are routed through the vCenter Server infrastructure, allowing attackers to circumvent intended access controls and gain access to restricted administrative endpoints that should only be available to authenticated administrators.
The technical exploitation of this vulnerability occurs through manipulation of URI parameters that traverse the reverse proxy layer, effectively allowing attackers to bypass authentication mechanisms that should normally validate access permissions. The flaw exists in how the vCenter Server processes and routes requests through its internal proxy components, where specific URI patterns can be crafted to skip authentication checks and directly access sensitive administrative interfaces. This type of vulnerability falls under the CWE-285 category of Improper Authorization, specifically manifesting as an authorization bypass through manipulation of URI components. The reverse proxy bypass mechanism creates a direct pathway for malicious actors to access restricted endpoints that normally require proper authentication and authorization validation before granting access to sensitive administrative functions.
From an operational impact perspective, this vulnerability presents a severe threat to virtual infrastructure security as it allows network-based attackers to access critical vCenter Server administrative interfaces without proper authentication. The implications extend beyond simple unauthorized access, as attackers could potentially manipulate virtual machine configurations, access sensitive configuration data, or perform administrative actions that could compromise entire virtualized environments. The vulnerability affects the core security model of vCenter Server by undermining the trust boundary that separates authenticated administrators from unauthorized network entities, potentially enabling attackers to escalate privileges and gain control over entire virtual infrastructures. This represents a significant concern for organizations relying on vCenter Server for managing their VMware virtual environments, as it could lead to complete compromise of virtual infrastructure management capabilities.
Organizations should implement immediate mitigations including applying the latest VMware patches that address this specific reverse proxy bypass vulnerability, reviewing and hardening reverse proxy configurations to prevent URI manipulation, and implementing network segmentation controls that limit direct access to vCenter Server ports. Security teams should also conduct thorough access control reviews to ensure that administrative endpoints are properly protected and monitor for suspicious URI patterns that may indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1078 Valid Accounts and T1566 Phishing, as exploitation typically involves bypassing authentication mechanisms to gain access to privileged accounts and systems. Organizations should also consider implementing additional network monitoring controls that can detect anomalous URI patterns and unauthorized access attempts to vCenter Server administrative endpoints, as the vulnerability specifically targets the proxy layer that handles URI routing and access control decisions.