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20Track

ModSecurity v3 XML Request Body Processor Uninitialized Pointer Dereference Vulnerability

owasp-modsecurity ModSecurity · CVE-2026-73857 ETK-2026-3995 EUVD-2026-120508 GHSA-JX3R-PHVX-2JMJ
0 news outlets1 CERTs and agencies0 research labs

Assessment: Track

SSVC decision points: exploitation none, automatable yes, technical impact partial, deployment low.

What is it?

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.

Evidence

Official warnings1National CERTs, government cyber security agencies and the vendor’s own advisories

Exploitation

  • Exploit code published (not verified by us)
  • Exploited in the wild (confirmed by a source)
  • Listed as known exploited (CISA KEV)
CVSS
7.5
EPSS
0.4%
First seen
22 h ago
Status
confirmed

All owasp-modsecurity vulnerabilities