Recently, a security vulnerability was identified in ModSecurity, a popular web application firewall by OWASP (Open Web Application Security Project) used to protect websites and applications. The issue involves how ModSecurity handles empty XML tags when the xml to arguments feature is enabled, potentially causing a segmentation fault that could disrupt service.
In ModSecurity versions 2.9.9 and above, if the SecParseXmlIntoArgs setting is enabled (On or OnlyArgs), and the server receives an XML request containing an empty tag (e.g., ), this can trigger a segmentation fault — a type of crash that can lead to server downtime.
An attacker could exploit this flaw by sending specially crafted XML payloads, potentially causing denial-of-service (DoS) conditions through crashes and/or impacting server stability. The default value of SecParseXmlIntoArgs is Off, so systems with this setting disabled are not affected.
Recommended Mitigations
Update to the latest version: The patched release, 2.9.11, addresses this vulnerability. If immediate patch application isn’t feasible, ensure SecParseXmlIntoArgs is set to Off in your ModSecurity configuration. This disables the problematic feature and prevents the crash.
Regularly update your security tools and software to incorporate the latest patches. If critical applications, stay updated on notices and releases by developer/manufacturer. And monitoring your systems for unusual activity or crashes could help in early finding of exploitation attempts.
Staying ahead of vulnerabilities like this is crucial for maintaining the security and stability of your web infrastructure. Learn more on
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