CVE-2010-4624 in MyBB
Summary
by MITRE
MyBB (aka MyBulletinBoard) before 1.4.12 allows remote authenticated users to bypass intended restrictions on the number of [img] MyCodes by editing a post after it has been created.
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Analysis
by VulDB Data Team • 10/07/2021
The vulnerability identified as CVE-2010-4624 affects MyBulletinBoard versions prior to 1.4.12, representing a significant security flaw in the forum software's access control mechanisms. This issue manifests as an authorization bypass that allows authenticated users to circumvent intended limitations on the use of [img] MyCodes within posts. The vulnerability specifically targets the validation process that should restrict the number of image tags permitted in forum posts, creating a potential vector for abuse that could impact both system performance and content integrity. The flaw exists in the post editing functionality where the system fails to re-evaluate the MyCode restrictions after a post has been modified, effectively allowing users to add unlimited image tags to previously posted content.
The technical implementation of this vulnerability stems from a design flaw in how MyBB handles post modifications and MyCode validation. When users create posts, the system properly enforces the configured limits on [img] MyCodes, but during the editing phase, the validation logic does not re-apply these restrictions. This creates a window where authenticated users can manipulate their posts to include an excessive number of image tags beyond the intended limits. The flaw operates at the application layer and requires authentication, meaning only users with valid accounts can exploit this vulnerability. This represents a classic case of insufficient input validation and access control enforcement, where the system fails to maintain consistent security policies across all user interactions with the content management system.
The operational impact of this vulnerability extends beyond simple content manipulation, potentially affecting system resources and user experience within the forum environment. An attacker could exploit this flaw to flood posts with numerous image tags, leading to increased bandwidth consumption, database storage requirements, and potential performance degradation for other users. The vulnerability could also be leveraged to create spam or abuse content that might be used to bypass content filtering systems or to generate excessive network traffic. In environments where MyBB serves as a community platform for sensitive discussions or where content moderation is critical, this flaw could undermine the integrity of the information sharing environment and potentially expose the system to additional attack vectors.
Organizations utilizing MyBulletinBoard should prioritize immediate remediation through the application of the official patch available in version 1.4.12 or later. The mitigation strategy should include comprehensive testing of the updated software to ensure that the MyCode validation logic properly enforces limits during both post creation and editing operations. System administrators should also implement monitoring to detect unusual patterns of image tag usage that might indicate exploitation attempts. This vulnerability aligns with CWE-602, which addresses client-side enforcement of server-side security checks, and falls under ATT&CK technique T1078 for valid accounts and privilege escalation through application-level manipulation. The remediation process should also include reviewing and updating security policies to ensure that all user interactions with content management features maintain consistent access control enforcement, particularly when modifications are made to existing content.