CVE-2011-5277 in Advanced Forum Signatures
Summary
by MITRE
Multiple SQL injection vulnerabilities in signature.php in the Advanced Forum Signatures (aka afsignatures) plugin 2.0.4 for MyBB allow remote attackers to execute arbitrary SQL commands via the (1) afs_type, (2) afs_background, (3) afs_showonline, (4) afs_bar_left, (5) afs_bar_center, (6) afs_full_line1, (7) afs_full_line2, (8) afs_full_line3, (9) afs_full_line4, (10) afs_full_line5, or (11) afs_full_line6 parameter. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.
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Analysis
by VulDB Data Team • 05/09/2026
The vulnerability identified as CVE-2011-5277 represents a critical SQL injection flaw within the Advanced Forum Signatures plugin version 2.0.4 for MyBB bulletin board systems. This vulnerability affects multiple parameters within the signature.php file, creating a wide attack surface that allows remote attackers to execute arbitrary SQL commands against the underlying database. The affected parameters include afs_type, afs_background, afs_showonline, and six sequential line parameters from afs_full_line1 through afs_full_line6, indicating a comprehensive injection vector across various signature display elements. The vulnerability stems from insufficient input validation and sanitization of user-supplied data passed to database queries without proper escaping or parameterization mechanisms.
From a technical perspective, this vulnerability operates under CWE-89 which classifies SQL injection as a weakness where untrusted data is incorporated into SQL commands without proper sanitization. The attack vector leverages the fact that user input for signature customization fields is directly concatenated into SQL queries without adequate protection measures. When attackers manipulate these parameters through HTTP requests, they can inject malicious SQL payloads that bypass authentication mechanisms, extract sensitive data, modify database records, or even execute system commands depending on the database configuration and privileges. The vulnerability's impact extends beyond simple data theft as it can enable complete database compromise and potentially lead to full system takeover.
The operational impact of this vulnerability is severe for any MyBB installation utilizing the affected plugin, as it provides attackers with persistent access to the forum's database infrastructure. Remote exploitation means that attackers do not require physical access or local privileges to exploit the vulnerability, making it particularly dangerous for publicly accessible forums. The attack could result in unauthorized data modification, user account compromise, forum content manipulation, and potential data exfiltration. Given that signature fields are commonly used by forum members for customization, the attack surface is naturally broad, and the vulnerability could be exploited through normal forum interaction without requiring specialized tools or techniques.
Security mitigations for this vulnerability should prioritize immediate patching of the affected plugin to version 2.0.5 or later, which contains proper input validation and sanitization measures. Organizations should implement proper parameterized queries and input validation for all user-supplied data before database insertion, following OWASP SQL Injection Prevention guidelines. Network-based mitigations such as web application firewalls can provide additional protection layers, though they should not replace proper code-level fixes. Regular security audits of third-party plugins and maintaining updated software versions are essential practices to prevent similar vulnerabilities. The vulnerability also highlights the importance of secure coding practices and input validation, aligning with ATT&CK technique T1190 which covers exploitation of vulnerabilities in web applications through SQL injection attacks.