CVE-2022-24734 is a Remote Code Execution (RCE) vulnerability affecting MyBB forum software versions from 1.2.0 up to, but not including, 1.8.30. MyBB is an open-source forum platform widely used for online community discussions. The vulnerability arises from improper validation in the Admin Control Panel's (Admin CP) Settings management module. Specifically, the module fails to correctly validate the type of settings being inserted or updated. This flaw allows an attacker with administrative privileges—specifically the 'Can manage settings?' permission—to create or modify settings of the 'php' type. These 'php' type settings contain PHP code that is executed when the Change Settings page is accessed. The setting data is stored in the database column 'mybb_settings.optionscode' as a string that includes the setting type and options separated by newline characters. Since support for the 'php' setting type was introduced in MyBB 1.2.0 for internal and plugin use, the lack of validation enables malicious PHP code injection and execution within the context of the web server. This can lead to full system compromise depending on the privileges of the web server user. The vulnerability is resolved in MyBB version 1.8.30. No known workarounds exist, and no public exploits have been reported in the wild to date. The vulnerability is classified under CWE-94 (Improper Control of Generation of Code), indicating a code injection flaw due to insufficient input validation and control over dynamically generated code execution.

For European organizations using vulnerable versions of MyBB, this vulnerability poses a significant risk. If an attacker gains or already possesses administrative access with the 'Can manage settings?' permission, they can execute arbitrary PHP code on the server hosting the forum. This can lead to complete compromise of the web application, unauthorized data access, data manipulation, or pivoting to other internal systems. Given that forums often contain sensitive user data, including personal information and private communications, confidentiality and integrity are at risk. Additionally, availability may be impacted if attackers deploy destructive payloads or ransomware. The impact is particularly critical for organizations relying on MyBB for customer engagement, internal collaboration, or public communications, as exploitation could damage reputation and lead to regulatory compliance issues under GDPR. Since exploitation requires administrative access, the threat is somewhat mitigated by the need for privileged credentials; however, insider threats or credential compromise scenarios remain concerning. The lack of known exploits in the wild reduces immediate risk but does not eliminate it, especially as attackers may develop exploits over time.

1. Upgrade MyBB installations to version 1.8.30 or later, where this vulnerability is patched. This is the most effective mitigation. 2. Restrict and audit Admin CP access rigorously, ensuring only trusted personnel have the 'Can manage settings?' permission. Implement strong authentication mechanisms such as multi-factor authentication (MFA) for admin accounts. 3. Monitor and log all changes to settings within the Admin CP to detect unauthorized or suspicious modifications. 4. If upgrading immediately is not feasible, consider isolating the MyBB server within a segmented network zone with strict access controls to limit potential lateral movement. 5. Regularly review installed plugins and custom code to ensure they do not introduce similar risks, especially those that might leverage the 'php' setting type. 6. Employ web application firewalls (WAFs) with custom rules to detect and block unusual admin panel requests that attempt to inject PHP code. 7. Conduct periodic security audits and penetration tests focusing on admin functionalities to identify potential privilege escalations or misuse. 8. Educate administrators on secure configuration management and the risks of granting excessive permissions.