CVE-2025-47947Public exploitNetwork attack vector

Denial of service via repeated sanitization queuing

Published May 21, 2025 · Updated May 22, 2025

Denial of service in ModSecurity 2.9.8 and earlier allows remote attackers to exhaust Apache memory with crafted JSON requests. The mod_security2 JSON processor expands all request variables before each matching sanitiseMatchedBytes action repeatedly appends the entire set to a dynamically growing APR table. An exposed Apache endpoint is affected only when audit logging and JSON body processing are enabled and a matching rule uses that action; repeated requests can exhaust CPU and memory until Apache fails.

CVSS severity7.5
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in ModSecurity 2.9.8 and earlier allows remote attackers to exhaust Apache memory with crafted JSON requests. The mod_security2 JSON processor expands all request variables before each matching sanitiseMatchedBytes action repeatedly appends the entire set to a dynamically growing APR table. An exposed Apache endpoint is affected only when audit logging and JSON body processing are enabled and a matching rule uses that action; repeated requests can exhaust CPU and memory until Apache fails.

The record

CVE
CVE-2025-47947
Published
May 21, 2025
Updated
May 22, 2025
Vendor
OWASP ModSecurity
Product
ModSecurity
Classifications
CWE-1050, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2025CVE publishedPublication date reported by the CVE source.
  2. May 22, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=<= 2.9.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OWASP ModSecurity · ModSecurityversion=<= 2.9.8

Published CVSS scores

7.5GitHub Maintainer CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1050Excessive Platform Resource Consumption within a Loop
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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