CVE-2021-41099 : Exploit Details and Defense Strategies

Redis is an open source, in-memory database that persists on disk. An integer overflow bug in the underlying string library can corrupt the heap, potentially leading to denial of service or remote code execution. The vulnerability involves altering the proto-max-bulk-len configuration parameter and crafting network payloads or commands. Redis versions 6.2.6, 6.0.16, and 5.0.14 address this issue. Mitigation can be achieved by restricting users from modifying the said configuration parameter.

Understanding CVE-2021-41099

This section delves into the core details of the CVE-2021-41099 vulnerability in Redis.

What is CVE-2021-41099?

The CVE-2021-41099 vulnerability entails an integer overflow bug in Redis that can be exploited to disrupt services or execute remote code. By manipulating the proto-max-bulk-len config value and constructing specific network inputs, bad actors can trigger this bug.

The Impact of CVE-2021-41099

The vulnerability has a high impact, categorized by a CVSS base score of 7.5. Its exploitation can lead to denial of service or remote code execution on affected Redis systems.

Technical Details of CVE-2021-41099

Explore the technical specifics of the Redis vulnerability.

Vulnerability Description

The bug arises from an integer overflow in the string library, allowing attackers to corrupt heap memory through crafted inputs, potentially leading to service disruptions or code execution.

Affected Systems and Versions

Product: Redis
Vendor: Redis
Vulnerable Versions:
< 5.0.14

= 6.0.0, < 6.0.16

= 6.2.0, 6.2.6

Exploitation Mechanism

Attackers can exploit this vulnerability by manipulating the proto-max-bulk-len configuration to trigger heap corruption, enabling denial of service or remote code execution.

Mitigation and Prevention

Learn how to protect your Redis installation from CVE-2021-41099.

Immediate Steps to Take

Update Redis to versions 6.2.6, 6.0.16, or 5.0.14 to patch the vulnerability
Implement ACL to restrict unprivileged users from modifying the proto-max-bulk-len parameter

Long-Term Security Practices

Regularly monitor and apply security updates for Redis
Conduct security training for users on safe configuration practices
Enable ACLs to enforce access controls

Patching and Updates

Ensure timely installation of Redis updates to address security vulnerabilities.