CVE-2021-27279 : Exploit Details and Defense Strategies

MyBB before 1.8.25 is vulnerable to stored cross-site scripting (XSS) attacks through nested [email] tags with MyCode (BBCode).

Understanding CVE-2021-27279

This CVE ID is assigned to a security vulnerability found in MyBB versions prior to 1.8.25 that allows an attacker to execute stored XSS attacks.

What is CVE-2021-27279?

CVE-2021-27279 is a security flaw in MyBB forums where malicious users can insert harmful code into the system using nested [email] tags with MyCode.

The Impact of CVE-2021-27279

The vulnerability can lead to unauthorized access, data theft, cookie theft, and potentially full site takeover if exploited by an attacker.

Technical Details of CVE-2021-27279

This section covers specific technical aspects of the CVE.

Vulnerability Description

MyBB versions prior to 1.8.25 are susceptible to stored XSS attacks due to insufficient validation of [email] tags with MyCode.

Affected Systems and Versions

All MyBB versions before 1.8.25 are affected by this vulnerability.

Exploitation Mechanism

Attackers can leverage the vulnerability by inserting malicious code within [email] tags, exploiting the lack of proper validation in MyBB forums.

Mitigation and Prevention

Protect your systems and users from CVE-2021-27279 with these crucial steps.

Immediate Steps to Take

Update MyBB forums to version 1.8.25 or later to patch the vulnerability.
Regularly monitor forum activities for suspicious content or behavior.

Long-Term Security Practices

Educate forum users about safe posting practices and awareness of potential XSS risks.
Implement a Content Security Policy (CSP) to mitigate XSS attacks.

Patching and Updates

Stay proactive by keeping MyBB forums up to date with the latest security patches and versions.