OWASP ModSecurity up to 3.0.16 XML Parsing SAX end-element callback uninitialized pointer

Summaryinfo

A vulnerability classified as critical has been found in OWASP ModSecurity ModSecurity up to 3.0.16. Affected by this vulnerability is the function SAX end-element callback of the component XML Parsing. This manipulation causes uninitialized pointer. This vulnerability is handled as CVE-2026-73857. The attack can be initiated remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in OWASP ModSecurity ModSecurity up to 3.0.16. It has been declared as critical. Affected by this vulnerability is the function SAX end-element callback of the component XML Parsing. The manipulation with an unknown input leads to a uninitialized pointer vulnerability. The CWE definition for the vulnerability is CWE-824. The product accesses or uses a pointer that has not been initialized. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.15 until 3.0.17, XML request body processing with SecParseXmlIntoArgs set to On or OnlyArgs can leave XMLNodes::parsing_ctx_arg uninitialized in the SAX end-element callback. A single crafted unauthenticated HTTP request can make a worker dereference the pointer, resulting in a constant-value write to an attacker-controlled address. The resulting memory corruption can terminate the worker and may disclose memory or redirect execution. Earlier 3.0.x releases and ModSecurity 2.x do not use the affected path. This issue is fixed in version 3.0.17.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-73857 since 08/13/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 3.0.17 eliminates this vulnerability.

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Productinfo

Vendor

• OWASP ModSecurity

Name

• ModSecurity

Version

• 3.0.0
• 3.0.1
• 3.0.2
• 3.0.3
• 3.0.4
• 3.0.5
• 3.0.6
• 3.0.7
• 3.0.8
• 3.0.9
• 3.0.10
• 3.0.11
• 3.0.12
• 3.0.13
• 3.0.14
• 3.0.15
• 3.0.16

License

• open-source

CPE 2.3info

• 🔒
• 🔒
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CPE 2.2info

• 🔒
• 🔒
• 🔒

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