CVE-2021-32675 : What You Need to Know

This article provides detailed information about a Denial of Service (DoS) vulnerability in Redis, an open-source, in-memory database that persists on disk.

Understanding CVE-2021-32675

This section explores the impact, technical details, and mitigation strategies related to CVE-2021-32675.

What is CVE-2021-32675?

Redis, known for handling incoming Redis Standard Protocol requests, is susceptible to a DoS vulnerability. Specially crafted requests can cause the server to allocate significant memory, potentially exploited by unauthenticated users.

The Impact of CVE-2021-32675

The CVSS score for this vulnerability is 7.5 (High), with a network attack vector and high availability impact. Unauthenticated users can trigger excessive memory allocation, leading to DoS.

Technical Details of CVE-2021-32675

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

Vulnerability Description

The vulnerability arises from Redis parsing mechanisms which, when manipulated, can lead to memory overallocation during request handling, impacting server performance.

Affected Systems and Versions

Redis versions < 5.0.14, >= 6.0.0, < 6.0.16, and >= 6.2.0, < 6.2.6 are affected by this vulnerability, requiring immediate attention.

Exploitation Mechanism

Attackers can exploit this vulnerability by sending specially crafted requests over multiple connections, causing the server to allocate excessive memory and disrupt normal operations.

Mitigation and Prevention

This section outlines the steps to mitigate the CVE-2021-32675 vulnerability and secure Redis installations.

Immediate Steps to Take

To address this issue, users should update to Redis versions 6.2.6, 6.0.16, or 5.0.14. Alternatively, blocking access for unauthenticated users using network controls or enabling TLS authentication is recommended.

Long-Term Security Practices

Implement network access controls, firewalls, or security groups to restrict unauthorized access. Additionally, enforcing TLS and client-side certificate authentication enhances Redis security.

Patching and Updates

Stay informed about security updates and patches for Redis to address vulnerabilities promptly and maintain a secure Redis environment.