CVE-2022-39265 in MyBB
Summary
by MITRE • 10/06/2022
MyBB is a free and open source forum software. The _Mail Settings_ → Additional Parameters for PHP's mail() function mail_parameters setting value, in connection with the configured mail program's options and behavior, may allow access to sensitive information and Remote Code Execution (RCE). The vulnerable module requires Admin CP access with the `_Can manage settings?_` permission and may depend on configured file permissions. MyBB 1.8.31 resolves this issue with the commit `0cd318136a`. Users are advised to upgrade. There are no known workarounds for this vulnerability.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 06/28/2026
The vulnerability identified as CVE-2022-39265 affects MyBB forum software versions prior to 1.8.31, representing a critical security flaw that combines information disclosure and remote code execution capabilities. This vulnerability resides within the email configuration system of MyBB, specifically in the Mail Settings section where administrators can configure additional parameters for PHP's mail() function through the mail_parameters setting. The flaw stems from insufficient input validation and sanitization of user-supplied parameters that are directly passed to the underlying mail execution mechanism, creating a pathway for malicious actors to manipulate the system's email handling behavior.
The technical exploitation of this vulnerability requires administrative access to the MyBB Admin Control Panel with the specific permission to manage settings, which establishes a baseline attack vector that aligns with privilege escalation patterns documented in the ATT&CK framework under privilege escalation techniques. The vulnerability's impact extends beyond simple information disclosure as it enables full remote code execution through carefully crafted parameters that can be interpreted by the underlying mail program, allowing attackers to execute arbitrary commands on the server with the privileges of the web application user. This represents a severe degradation of the system's security posture, as the attack surface expands from typical web application vulnerabilities to include system-level command execution capabilities.
The operational impact of this vulnerability is particularly concerning given that it requires only administrative access rather than authentication as a regular user, meaning that attackers who have already compromised administrative credentials or gained access through other means can immediately leverage this flaw for devastating consequences. The vulnerability's dependency on configured file permissions adds another layer of complexity to the threat model, as attackers may be able to exploit the flaw more effectively when the web server has elevated privileges or when specific file permissions allow for more extensive command injection possibilities. This aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and CWE-20, which covers improper input validation, both of which are fundamental security weaknesses that enable command injection attacks.
The remediation for this vulnerability was implemented through the commit 0cd318136a in MyBB version 1.8.31, which introduced proper input sanitization and validation mechanisms for the mail_parameters configuration value. This fix ensures that user-supplied parameters are properly escaped and validated before being passed to the PHP mail() function, preventing the execution of unintended commands. Organizations utilizing MyBB should immediately upgrade to version 1.8.31 or later to mitigate this risk, as no effective workarounds exist for this vulnerability. The fix demonstrates the importance of proper input validation in security-critical functions, particularly when dealing with system-level commands that can be directly invoked through application interfaces. This vulnerability serves as a reminder of the critical importance of validating and sanitizing all user inputs that may be passed to system commands, as highlighted in industry best practices for preventing command injection attacks.