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CVE-2026-73857— ModSecurity v3 XML Request Body Processor Uninitialized Pointer Dereference Vulnerability

Quick assessment

Affected
owasp-modsecurity ModSecurity
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

ModSecurity 是一款开源、跨平台的 Web 应用防火墙（WAF）引擎，支持 Apache、IIS 和 Nginx。在版本 3.0.15 至 3.0.17 中，当将 SecParseXmlIntoArgs 配置为 On 或 OnlyArgs 并处理 XML 请求体时，SAX 的 end-element 回调函数中 XMLNodes::parsing_ctx_arg 可能未被初始化。攻击者可构造一条未经认证的 HTTP 请求，致使工作进程对该指针进行解引用，从而向攻击者控制的地址执行一个固定值的写入操作。由此

CVSS 7.5 · High
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I. Basic Information for CVE-2026-73857

Vulnerability Information
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Vulnerability Title
ModSecurity v3 XML Request Body Processor Uninitialized Pointer Dereference Vulnerability
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
owasp-modsecurity ModSecurity >= 3.0.15, < 3.0.17 -

II. Public POCs for CVE-2026-73857

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III. Intelligence Information for CVE-2026-73857

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Other References for CVE-2026-73857 (3)

Same Patch Batch · owasp-modsecurity · 2026-11-09 · 3 CVEs total

CVE-2026-61812 6.3 MEDIUM ModSecurity: HTML decoder missing entities, leading to evasion
CVE-2026-104259 5.4 MEDIUM ModSecurity: removeComments Transformation Fails to Strip Adjacent Comments, Enabling WAF

IV. Related Vulnerabilities

Same product: ModSecurity
Same vendor: owasp-modsecurity
Same weakness: CWE-787