CVE-2022-48279 in ModSecurity
Summary
by MITRE • 01/20/2023
In ModSecurity before 2.9.6 and 3.x before 3.0.8, HTTP multipart requests were incorrectly parsed and could bypass the Web Application Firewall. NOTE: this is related to CVE-2022-39956 but can be considered independent changes to the ModSecurity (C language) codebase.
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Analysis
by VulDB Data Team • 04/04/2025
The vulnerability identified as CVE-2022-48279 represents a critical flaw in ModSecurity's handling of HTTP multipart requests that directly impacts web application firewall effectiveness. This issue affects both the 2.9.x series prior to version 2.9.6 and the 3.x series prior to version 3.0.8, indicating a widespread problem within the ModSecurity codebase that has persisted across major version releases. The flaw specifically manifests in the parsing logic responsible for processing HTTP multipart content, which is commonly used in file uploads and form submissions within web applications.
The technical root cause of this vulnerability lies in improper parsing of HTTP multipart requests within the ModSecurity C language implementation. When the firewall encounters multipart content, the flawed parsing mechanism fails to correctly interpret the boundary delimiters and content structure, leading to incomplete or incorrect analysis of the request data. This parsing error creates opportunities for malicious content to slip through the security controls without proper inspection, effectively allowing attackers to bypass the intended protection mechanisms. The vulnerability operates at the protocol level where multipart boundaries are not properly validated or processed, enabling crafted requests to evade detection by the web application firewall.
The operational impact of CVE-2022-48279 is significant for organizations relying on ModSecurity as their primary web application firewall solution. Attackers can exploit this vulnerability to submit malicious payloads through multipart requests that would normally be flagged and blocked by the firewall. This bypass capability undermines the fundamental security posture of web applications protected by ModSecurity, potentially allowing for injection attacks, file upload vulnerabilities, and other malicious activities that target web application weaknesses. The vulnerability particularly affects applications that process file uploads or form submissions with multipart content, creating a window of opportunity for attackers to exploit other application vulnerabilities that would otherwise be prevented by proper firewall inspection.
Organizations should prioritize immediate remediation of this vulnerability by upgrading to ModSecurity versions 2.9.6 or 3.0.8 and later, which contain the necessary code fixes to properly parse HTTP multipart requests. The mitigation strategy should include comprehensive testing of the updated firewall configuration to ensure that legitimate traffic continues to be properly handled while malicious content is appropriately blocked. Security teams should also conduct thorough vulnerability assessments to identify any potential exploitation attempts that may have occurred during the period when the vulnerable version was in use, as the bypass capability could have allowed attackers to deploy previously blocked payloads. This vulnerability aligns with CWE-129 and CWE-134 categories related to input validation and improper handling of input boundaries, and may be mapped to ATT&CK techniques involving evasion and command and control operations where firewall bypasses enable more sophisticated attack delivery mechanisms.
The independent nature of this vulnerability from CVE-2022-39956 indicates that while both issues affect ModSecurity's multipart handling capabilities, they represent distinct code modifications that require separate remediation efforts. This distinction is important for organizations managing multiple security patches and updates, as it requires careful coordination to ensure that all related vulnerabilities are properly addressed. The vulnerability demonstrates the critical importance of proper HTTP protocol parsing in security tools, as even subtle flaws in request handling can create significant security gaps that attackers can exploit to undermine the effectiveness of web application protection mechanisms.