Bug 2570889 (CVE-2026-73857)

Summary:	CVE-2026-73857 modsecurity: ModSecurity: Denial of Service via crafted XML request
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in ModSecurity. When XML request body argument parsing is enabled, processing certain XML elements leaves an internal pointer uninitialized. A remote, unauthenticated attacker can exploit this flaw by sending a specially crafted HTTP request containing an XML payload. This causes memory corruption, leading to a Denial of Service (DoS) by crashing worker processes, and may potentially allow information disclosure or arbitrary code execution.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Bug Depends On:	2573142, 2573143
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Description OSIDB Bzimport 2026-11-10 20:28:55 UTC

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.