CVE-2021-21994 is a critical vulnerability affecting VMware ESXi, specifically within the Small Footprint CIM Broker (SFCB). This vulnerability allows for an authentication bypass, enabling malicious actors with network access to port 5989 to exploit the issue by sending specially crafted requests. With a CVSS score of 9.8, this vulnerability poses a significant risk to organizations, as it could lead to unauthorized access and manipulation of sensitive data.
Given the severity of this vulnerability, organizations should prioritize patching immediately. The potential for unauthorized access highlights the importance of proactive security measures and timely remediation.
Currently, there is no known public exploit for CVE-2021-21994 as per the latest intelligence data. However, the absence of known exploitation does not diminish the urgency for organizations to address this vulnerability.
Organizations using affected versions of VMware ESXi must ensure that they remain vigilant and monitor their systems for any indications of exploitation attempts as they work towards implementing the necessary patches.
Vulnerability Details
The vulnerability in question, CVE-2021-21994, pertains to an authentication bypass in SFCB as utilized in ESXi. The official description states that a malicious actor, with network access to port 5989, can bypass SFCB authentication by sending a specially crafted request.
This vulnerability has been assigned a CVSS score of 9.8, categorizing it as critical. It is classified under CWE-287, indicating a failure to adequately enforce authentication mechanisms.
The vulnerability affects several versions of VMware ESXi and Cloud Foundation, specifically versions of ESXi 6.5 and 6.7, as well as Cloud Foundation versions from 3.0 to 3.10.2.
Technical Analysis
The root cause of CVE-2021-21994 lies in improper authentication checks within the SFCB component. This allows an attacker to exploit the vulnerability remotely without requiring any privileges or user interaction, classifying the attack vector as network-based with low complexity.
The attack would require access to the network where the vulnerable ESXi host is located, allowing attackers to send crafted requests to the SFCB service running on port 5989.
The confidentiality, integrity, and availability impacts are assessed as high, making this vulnerability particularly dangerous if left unmitigated.
Risk & Impact Analysis
Risk to organizations includes potential unauthorized access to sensitive information and the ability to manipulate or disrupt services. The critical nature of this vulnerability, combined with a CVSS score of 9.8, signifies that organizations must act promptly to remediate.
The blast radius of this vulnerability is significant, as it could potentially affect multiple systems within an organization, particularly those relying on VMware ESXi and Cloud Foundation components.
With the KEV classification indicating no active exploitation, the urgency remains high, and organizations should incorporate this vulnerability into their immediate patching cycle.
The EPSS score of 0.00378 indicates a low probability of exploitation in the wild; however, this should not lead to complacency, as attackers continuously seek unpatched vulnerabilities.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
CVE-2021-21994 affects the following versions:
VMware ESXi 6.5 and 6.7, as well as VMware Cloud Foundation versions from 3.0 to 3.10.2 are impacted. Organizations should verify their systems and ensure they are running patched versions.
Mitigation & Remediation
Organizations should prioritize patching their VMware ESXi and Cloud Foundation instances to mitigate this vulnerability. The following actions are recommended:
1. Apply the latest security patches provided by VMware.
2. Utilize network segmentation to limit access to sensitive services.
3. Monitor logs for any unauthorized access attempts.
For further information on best practices in security assessments, organizations should consider engaging in penetration testing to identify similar weaknesses.
Detection Guidance
To detect potential exploitation of this vulnerability, organizations should monitor the following:
1. Logs related to authentication attempts on port 5989.
2. Anomalies in network traffic patterns that could indicate exploitation attempts.
3. Changes in system configurations that do not align with organizational policies.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-21994 lies in its demonstration of how critical vulnerabilities can arise from inadequate authentication mechanisms. Organizations must be vigilant in their security posture, regularly assessing and patching vulnerabilities.
This incident reinforces the necessity of implementing robust authentication controls and highlights the importance of continuous security assessments.
For further insights into vulnerability management, organizations should explore our resources on vulnerability management programs and effective remediation strategies.
Additionally, understanding the trends in vulnerability exploitation can be achieved through our studies on vulnerability exposure severity trends that provide insights into the evolving threat landscape.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
.webp)