CVE-2026-42268Public exploitNetwork attack vector

Unauthenticated server crash via empty operator input

Published May 12, 2026 · Updated May 12, 2026

Denial of service in OWASP ModSecurity 3.0.0 through 3.0.14 allows remote attackers to crash a protected server via an empty argument. In verify_ssn.cc and matching CPF and SVNR implementations, subtracting one from an empty input size wraps the loop bound; substr then throws an uncaught out_of_range exception that invokes process termination. Exposure requires libmodsecurity3 rules using @verifySSN, @verifyCPF, or @verifySVNR; mod_security2 and installations using only OWASP CRS rules are unaffected.

CVSS severity8.2
High
EPSS probability0.40%
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 OWASP ModSecurity 3.0.0 through 3.0.14 allows remote attackers to crash a protected server via an empty argument. In verify_ssn.cc and matching CPF and SVNR implementations, subtracting one from an empty input size wraps the loop bound; substr then throws an uncaught out_of_range exception that invokes process termination. Exposure requires libmodsecurity3 rules using @verifySSN, @verifyCPF, or @verifySVNR; mod_security2 and installations using only OWASP CRS rules are unaffected.

The record

CVE
CVE-2026-42268
Published
May 12, 2026
Updated
May 12, 2026
Vendor
OWASP ModSecurity
Product
ModSecurity
Classifications
CWE-191, CWE-248, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 2026CVE publishedPublication date reported by the CVE source.
  2. May 12, 2026Record 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=>= 3.0.0, < 3.0.15

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OWASP ModSecurity · ModSecurityversion=>= 3.0.0, < 3.0.15

Published CVSS scores

8.2GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5NIST NVDCVSS: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-191Integer Underflow (Wrap or Wraparound)
CWE-248Uncaught Exception
T1499Endpoint Denial of Service

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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