CVE-2021-22955 : What You Need to Know

A denial of service vulnerability (CWE-400) exists in Citrix ADC versions <13.0-83.27, <12.1-63.22, and 11.1-65.23 when used as a VPN or AAA virtual server, allowing attackers to disrupt Management GUI, Nitro API, and RPC communication.

Understanding CVE-2021-22955

This section provides insights into the impact, technical details, and mitigation strategies for CVE-2021-22955.

What is CVE-2021-22955?

CVE-2021-22955 is an unauthenticated denial of service vulnerability present in Citrix ADC, specifically affecting versions <13.0-83.27, <12.1-63.22, and 11.1-65.23 configured as VPN or AAA virtual servers. This vulnerability enables attackers to disrupt the normal functioning of key services, leading to a temporary interruption.

The Impact of CVE-2021-22955

The impact of CVE-2021-22955 can result in a temporary disruption of the Management GUI, Nitro API, and RPC communication within affected Citrix ADC versions. By exploiting this vulnerability, malicious actors can cause service interruptions, potentially affecting system availability and performance.

Technical Details of CVE-2021-22955

To understand how CVE-2021-22955 operates, it is crucial to delve into the vulnerability description, affected systems, versions, and the exploitation mechanism.

Vulnerability Description

The vulnerability allows unauthenticated attackers to launch denial of service attacks on vulnerable Citrix ADC instances, affecting key functionalities like Management GUI, Nitro API, and RPC communication.

Affected Systems and Versions

Citrix ADC versions <13.0-83.27, <12.1-63.22, and 11.1-65.23 configured as VPN or AAA virtual servers are susceptible to this denial of service vulnerability.

Exploitation Mechanism

By exploiting CVE-2021-22955, threat actors can initiate unauthenticated denial of service attacks, causing a temporary disruption in the mentioned Citrix ADC services.

Mitigation and Prevention

Protecting systems from CVE-2021-22955 requires immediate action and long-term security measures.

Immediate Steps to Take

Immediately apply patches or workarounds provided by Citrix to mitigate the vulnerability's impact. Monitor network traffic for any signs of exploitation.

Long-Term Security Practices

Regularly update Citrix ADC versions and implement security best practices to prevent future vulnerabilities. Conduct security audits and assessments periodically.

Patching and Updates

Stay informed about security updates from Citrix and apply patches promptly to safeguard against known vulnerabilities like CVE-2021-22955.