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CVE-2026-73856— ModSecurity: Response Body Inspection Bypass

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 是一款开源的跨平台 Web 应用防火墙（WAF）引擎，支持 Apache、IIS 和 Nginx。在版本 3.0.0 至 3.0.17 中，src/transaction.cc 在将响应 Content-Type 值与 SecResponseBodyMimeType 条目进行比较时，采用了区分大小写的匹配方式。因此，若响应媒体类型采用混合大小写写法，但其语义与已配置的纯小写类型等价，ModSecurity 可能将其视为未配置项，从而跳过对响应正文（RESPONSE_BODY）的检查。未经认证

CVSS 8.6 · High

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
owasp-modsecurity ModSecurity >= 3.0.0, < 3.0.17 affected
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I. Basic Information for CVE-2026-73856

Vulnerability Information
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Vulnerability Title
ModSecurity: Response Body Inspection Bypass
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 3.0.0 until 3.0.17, src/transaction.cc compares a response Content-Type value against SecResponseBodyMimeType entries case-sensitively. A mixed-case response media type that is semantically equivalent to a configured lowercase type can therefore be treated as unconfigured, causing ModSecurity to skip RESPONSE_BODY inspection. An unauthenticated requester can then receive response content that a phase 4 rule would otherwise block, including sensitive error or debug data. 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:C/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
大小写敏感处理不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
owasp-modsecurity ModSecurity >= 3.0.0, < 3.0.17 -

II. Public POCs for CVE-2026-73856

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-73856

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Other References for CVE-2026-73856 (3)

Same Patch Batch · owasp-modsecurity · 2026-11-05 · 4 CVEs total

CVE-2026-104269 8.6 HIGH ModSecurity: RFC 2231 `filename*` Parameter Bypasses Multipart Filename Rules on RFC-Compl
CVE-2026-103932 5.8 MEDIUM ModSecurity: PCRE2 `@rxGlobal` match-limit errors are converted to no-match
CVE-2026-61813 3.7 LOW ModSecurity: Incorrect libcurl TLS hostname verification setting in HttpsClient::download

IV. Related Vulnerabilities

Same product: ModSecurity
Same vendor: owasp-modsecurity
Same weakness: CWE-178