CVE-2021-22991 Explained : Impact and Mitigation

A buffer overflow vulnerability, CVE-2021-22991 affects various versions of BIG-IP by F5. Exploiting this flaw could lead to DoS attacks and potentially remote code execution.

Understanding CVE-2021-22991

This CVE impacts BIG-IP products by F5 due to mishandling of undisclosed requests, potentially resulting in a buffer overflow and DoS attacks, with the possibility of remote code execution.

What is CVE-2021-22991?

CVE-2021-22991 is a vulnerability in BIG-IP versions before 16.0.1.1, 15.1.2.1, 14.1.4, 13.1.3.6, and 12.1.5.3, where improper handling of virtual server requests by TMM can trigger a buffer overflow, leading to DoS attacks and potential RCE.

The Impact of CVE-2021-22991

Exploiting this vulnerability could result in denial of service attacks, potential bypass of URL access controls, and in certain scenarios, remote code execution, posing significant security risks to affected systems.

Technical Details of CVE-2021-22991

This section delves deeper into the vulnerability, affected systems, and the exploitation mechanism.

Vulnerability Description

The flaw arises from incorrectly handling requests to virtual servers by TMM URI normalization, causing a buffer overflow that may result in DoS attacks, potential bypass of URL-based access controls, and remote code execution.

Affected Systems and Versions

BIG-IP versions impacted include 16.0.x before 16.0.1.1, 15.1.x before 15.1.2.1, 14.1.x before 14.1.4, 13.1.x before 13.1.3.6, and 12.1.x before 12.1.5.3.

Exploitation Mechanism

By sending undisclosed requests to a virtual server, attackers can trigger the buffer overflow in TMM URI normalization, potentially leading to DoS attacks and exploitation for remote code execution.

Mitigation and Prevention

To safeguard systems, immediate steps, long-term security practices, and the importance of patching and updates are detailed below.

Immediate Steps to Take

Organizations are advised to apply security patches promptly, restrict network access, monitor for malicious activities, and implement network segmentation.

Long-Term Security Practices

Regular security assessments, network monitoring, access control measures, and employee training on cybersecurity best practices are crucial for long-term protection.

Patching and Updates

F5 has released patches to address CVE-2021-22991 in affected versions of BIG-IP. Ensure timely application of these patches to mitigate the risk of exploitation and enhance system security.