CVE-2009-4448 in MyBB
Summary
by MITRE
inc/functions_time.php in MyBB (aka MyBulletinBoard) 1.4.10, and possibly earlier versions, allows remote attackers to cause a denial of service (CPU consumption) via a crafted request with a large year value, which triggers a long loop, as reachable through member.php and possibly other vectors.
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Analysis
by VulDB Data Team • 09/26/2025
The vulnerability identified as CVE-2009-4448 affects MyBulletinBoard version 1.4.10 and potentially earlier releases, representing a significant denial of service weakness in the inc/functions_time.php file. This flaw demonstrates a classic example of a resource exhaustion attack that can severely impact system availability and performance. The vulnerability arises from inadequate input validation and sanitization within the time processing functions, creating a condition where malicious actors can exploit the system's handling of date and time parameters. The flaw specifically targets the year value parameter in date parsing operations, where a crafted request containing an excessively large year value triggers an unintended computational loop that consumes substantial cpu resources.
The technical implementation of this vulnerability stems from the way MyBB processes date inputs through its member.php script and potentially other entry points. When a malicious user submits a request with an unusually large year value, the system's time parsing function enters a prolonged loop that iterates through an excessive number of iterations. This behavior directly violates the principle of input validation and demonstrates a lack of proper bounds checking for numeric parameters. The vulnerability operates under the category of resource exhaustion as defined by CWE-400, specifically manifesting as a computational complexity issue where the processing time grows exponentially with input size. The attack vector can be executed remotely without requiring authentication, making it particularly dangerous in web environments where the application is exposed to untrusted users.
The operational impact of CVE-2009-4448 extends beyond simple service disruption to potentially compromise the entire web application infrastructure. When exploited, the vulnerability causes sustained high cpu utilization that can affect not only the targeted MyBB installation but also impact other applications running on the same server. The denial of service condition can persist for extended periods, depending on the magnitude of the crafted year value and the system's computational capacity. This vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion. The attack's effectiveness is amplified by the fact that it requires minimal technical expertise to execute, making it a popular choice among threat actors seeking to disrupt services. Additionally, the vulnerability demonstrates poor defensive programming practices and highlights the importance of implementing proper input validation and early termination conditions in time processing functions.
Mitigation strategies for CVE-2009-4448 should focus on implementing robust input validation and boundary checking mechanisms within the affected time processing functions. System administrators should immediately apply the vendor-provided patch or upgrade to a version that addresses this vulnerability, as the flaw exists in the core time parsing logic of the application. The implementation of rate limiting and request validation controls can provide additional defense in depth measures to prevent exploitation attempts. Security monitoring should include detection of unusual cpu utilization patterns and suspicious request parameters that may indicate exploitation attempts. Organizations should also consider implementing web application firewalls that can identify and block malformed date parameters before they reach the vulnerable application logic. The vulnerability underscores the critical importance of proper error handling and input sanitization in web applications, particularly in functions that process user-supplied data, as outlined in the OWASP Top Ten security principles and the CWE guidelines for secure coding practices.