CVE-2021-21995 : What You Need to Know

OpenSLP as used in VMware ESXi and VMware Cloud Foundation has a denial-of-service vulnerability that allows a malicious actor to trigger a heap out-of-bounds read. This can lead to a denial-of-service condition by exploiting port 427 on ESXi.

Understanding CVE-2021-21995

This CVE identifies a denial-of-service vulnerability affecting VMware ESXi and VMware Cloud Foundation due to a heap out-of-bounds read issue in OpenSLP.

What is CVE-2021-21995?

CVE-2021-21995 is an authentication bypass vulnerability in OpenSLP service used in VMware ESXi and VMware Cloud Foundation. A remote attacker with access to port 427 on ESXi can exploit this flaw to cause a denial-of-service condition.

The Impact of CVE-2021-21995

Exploitation of this vulnerability could result in a denial-of-service, rendering affected systems unresponsive and potentially disrupting critical services.

Technical Details of CVE-2021-21995

This section dives into the vulnerability description, affected systems and versions, and the exploitation mechanism.

Vulnerability Description

The vulnerability in OpenSLP allows a malicious actor to perform a heap out-of-bounds read, triggering a denial-of-service condition on VMware ESXi and VMware Cloud Foundation.

Affected Systems and Versions

VMware ESXi versions 7.0 before ESXi70U2-17630552, 6.7 before ESXi670-202103101-SG, 6.5 before ESXi650-202107401-SG, and VMware Cloud Foundation versions 4.x, 3.x before 3.10.2 are impacted.

Exploitation Mechanism

An attacker with network access to port 427 on ESXi can exploit this vulnerability by triggering a heap out-of-bounds read in the OpenSLP service, leading to a denial-of-service.

Mitigation and Prevention

To protect systems from CVE-2021-21995, immediate steps, long-term security practices, and patching recommendations are essential.

Immediate Steps to Take

Organizations should apply the latest security updates and patches provided by VMware to mitigate the risk of exploitation associated with CVE-2021-21995.

Long-Term Security Practices

Implement network segmentation, access controls, and regular security assessments to enhance the overall security posture of VMware ESXi and VMware Cloud Foundation deployments.

Patching and Updates

Ensure timely application of security patches and updates from VMware to address known vulnerabilities like CVE-2021-21995 and strengthen the security of VMware ESXi and VMware Cloud Foundation environments.