CVE-2019-9650 in Upcoming Events Plugin
Summary
by MITRE
An XSS issue was discovered in upcoming_events.php in the Upcoming Events plugin before 1.33 for MyBB via a crafted name for an event.
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Analysis
by VulDB Data Team • 09/02/2025
The vulnerability identified as CVE-2019-9650 represents a cross-site scripting flaw within the Upcoming Events plugin for MyBB forum software, specifically affecting versions prior to 1.33. This issue resides in the upcoming_events.php script which handles event display functionality within the plugin's interface. The vulnerability stems from inadequate input validation and output sanitization mechanisms that fail to properly escape user-supplied data before rendering it in web pages. Attackers can exploit this weakness by crafting malicious event names containing script tags or other malicious payloads that get executed in the context of other users' browsers when the event information is displayed.
The technical nature of this vulnerability aligns with CWE-79, which specifically addresses Cross-Site Scripting flaws in web applications. This classification indicates that the plugin fails to properly neutralize user-controllable input data before incorporating it into dynamically generated web content. The attack vector involves an authenticated user with sufficient privileges to create or modify events within the MyBB forum system, making this a medium to high severity concern depending on the forum's user management policies. The vulnerability allows for persistent XSS attacks where malicious scripts can be stored on the server and executed whenever affected pages are accessed by other users.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, redirection to malicious sites, and data exfiltration. In a typical forum environment, where users may have varying levels of trust and the plugin likely serves as a community engagement tool, this vulnerability could be exploited to compromise user sessions and potentially escalate privileges. The persistent nature of the vulnerability means that once an attacker successfully injects malicious code through a crafted event name, the payload will execute for all users who view the affected event information, making it particularly dangerous in high-traffic forum environments.
Mitigation strategies for CVE-2019-9650 should prioritize immediate patching to version 1.33 or later of the Upcoming Events plugin, as this represents the most effective defense against the known vulnerability. Organizations should also implement additional security measures including input validation at multiple layers, output encoding for all user-generated content, and regular security audits of third-party plugins. Network monitoring should be enhanced to detect suspicious activity related to event creation and modification, while administrators should consider implementing content security policies to further limit the execution of malicious scripts. The vulnerability also highlights the importance of adhering to secure coding practices and following the ATT&CK framework's guidance on preventing web application vulnerabilities through proper input sanitization and output encoding mechanisms.