CVE-2021-41115 : What You Need to Know

Zulip is an open-source team chat server that allows organization administrators to configure 'linkifiers.' A vulnerability in Zulip versions prior to 4.7 enables denial-of-service attacks through regular expression complexity.

Understanding CVE-2021-41115

In versions of Zulip before 4.7, a vulnerability exists that could be exploited by organization administrators to disrupt the service through regular expression complexity attacks.

What is CVE-2021-41115?

Zulip allows users to create links using regular expressions. However, malicious administrators could exploit this feature to conduct denial-of-service attacks by setting up overly complex regular expressions.

The Impact of CVE-2021-41115

The vulnerability can be leveraged by malicious actors to perform denial-of-service attacks on Zulip servers, potentially disrupting communication and service availability.

Technical Details of CVE-2021-41115

This section delves into the technical aspects of the CVE for a better understanding of the vulnerability.

Vulnerability Description

The vulnerability arises from insufficient protection against regular expression denial-of-service attacks within Zulip's 'linkifiers' configuration.

Affected Systems and Versions

Product: Zulip
Vendor: Zulip
Versions Affected: < 4.7

Exploitation Mechanism

Malicious administrators could configure quadratic-time regular expressions within 'linkifiers,' leading to denial-of-service via regular expression complexity attacks.

Mitigation and Prevention

To safeguard systems from CVE-2021-41115 and mitigate potential risks, the following steps are recommended:

Immediate Steps to Take

Upgrade Zulip to version 4.7 or newer to patch the vulnerability.

Long-Term Security Practices

Regularly monitor and update systems to ensure all security patches are applied promptly.

Patching and Updates

Keep software and systems up to date by applying relevant security patches and updates.