CVE-2021-28651 Explained : Impact and Mitigation

An issue was discovered in Squid before 4.15 and 5.x before 5.0.6 that allows a denial of service due to a buffer-management bug. This vulnerability arises when resolving a request with the urn: scheme, where the parser leaks memory and can be exploited to trigger significant memory consumption.

Understanding CVE-2021-28651

This section provides insight into the nature and impact of CVE-2021-28651.

What is CVE-2021-28651?

The CVE-2021-28651 vulnerability is a buffer-management bug in Squid versions prior to 4.15 and 5.0.6, leading to a denial of service. Exploitation of this flaw involves memory leakage during the resolution of a request using the urn: scheme, resulting in potential memory exhaustion via an unspecified attack methodology.

The Impact of CVE-2021-28651

The impact of this vulnerability is the potential for attackers to launch denial-of-service attacks by triggering excessive memory consumption. By exploiting the buffer-management bug in affected Squid versions, a malicious actor could disrupt the normal functioning of the application or system.

Technical Details of CVE-2021-28651

Explore the technical specifics regarding the CVE-2021-28651 vulnerability.

Vulnerability Description

The vulnerability in Squid versions before 4.15 and 5.0.6 arises due to inadequate buffer management during the resolution of requests with the urn: scheme. This results in memory leakage, which can be manipulated to exhaust system resources.

Affected Systems and Versions

The vulnerability impacts Squid versions earlier than 4.15 and 5.0.6. Systems using these versions are at risk of facing denial-of-service attacks through exploitation of the memory leakage flaw.

Exploitation Mechanism

By leveraging the buffer-management bug in Squid, threat actors can deliberately trigger memory leakage when processing urn: scheme requests. This can be exploited to consume excessive memory resources, leading to denial-of-service conditions.

Mitigation and Prevention

Learn how to address and mitigate the CVE-2021-28651 vulnerability effectively.

Immediate Steps to Take

Users and administrators are advised to update Squid to versions 4.15 or 5.0.6 or later to eliminate the buffer-management bug and prevent potential denial-of-service attacks. Proper configuration of Squid settings can also help reduce the risk of exploitation.

Long-Term Security Practices

To enhance long-term security, organizations should maintain up-to-date software versions, regularly monitor for security advisories, and implement proactive security measures to defend against emerging threats.

Patching and Updates

Regularly check for security patches and updates released by the Squid project to address known vulnerabilities, including CVE-2021-28651. Timely patching of software can significantly reduce the risk of exploitation and enhance the overall security posture of systems.