CVE-2021-22019 in vCenter Server
Summary
by MITRE • 09/24/2021
The vCenter Server contains a denial-of-service vulnerability in VAPI (vCenter API) service. A malicious actor with network access to port 5480 on vCenter Server may exploit this issue by sending a specially crafted jsonrpc message to create a denial of service condition.
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Analysis
by VulDB Data Team • 10/02/2021
The vulnerability identified as CVE-2021-22019 represents a critical denial-of-service weakness within VMware vCenter Server's VAPI (vCenter API) service component. This flaw exists in the server's handling of JSON-RPC messages, creating an exploitable condition that can be leveraged by remote attackers to disrupt normal operations. The vulnerability specifically affects the vCenter Server's communication interface on port 5480, which serves as the primary endpoint for API interactions and management operations within VMware's virtualization environment.
The technical implementation of this vulnerability stems from insufficient input validation and processing within the VAPI service's JSON-RPC message handling mechanism. When a malicious actor sends a specially crafted JSON-RPC message to the targeted port, the vCenter Server fails to properly validate or sanitize the incoming data, leading to a condition where the service becomes unresponsive or crashes entirely. This improper handling of malformed JSON-RPC requests creates a predictable exploitation pattern that allows attackers to repeatedly trigger the service disruption without requiring authentication or elevated privileges. The vulnerability operates at the application layer and requires only network connectivity to the target system's designated port.
The operational impact of CVE-2021-22019 extends beyond simple service interruption, as it can severely compromise the availability of virtualized environments managed by vCenter Server. Organizations relying on VMware infrastructure for their data center operations face significant risk of service degradation or complete outages when this vulnerability is exploited. The denial-of-service condition affects not only the vCenter Server itself but also impacts all virtual machines and services dependent on the management platform. This vulnerability particularly threatens organizations with limited network segmentation, as attackers can exploit it from external networks without requiring privileged access to the system. The cascading effects can include disruption of backup operations, automated provisioning workflows, and monitoring systems that depend on vCenter Server availability.
Security professionals should consider this vulnerability in the context of broader attack patterns documented in the MITRE ATT&CK framework, specifically relating to service disruption and availability attacks under the T1499 category. The vulnerability aligns with CWE-20, which describes "Improper Input Validation" as the underlying weakness, making it particularly concerning for enterprise environments where vCenter Server serves as a critical management component. Organizations should implement immediate mitigations including network segmentation to restrict access to port 5480, firewall rules to limit connections to trusted sources only, and proactive patch management to address the vulnerability. Additionally, monitoring systems should be configured to detect unusual patterns of JSON-RPC traffic that might indicate exploitation attempts, as the vulnerability creates predictable behavioral signatures that can be detected through network analysis and log monitoring.