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CVE-2026-52747: Owasp Modsecurity Security Vulnerability (CVSS 8.6)

CVE-2026-52747 is a high severity security vulnerability in Owasp Modsecurity with a CVSS score of 8.6. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Last updated: Jul 14, 2026

Quick answer

Direct answer

CVE-2026-52747 is a high severity security vulnerability in Owasp Modsecurity with a CVSS score of 8.6. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Risk scores

CVSS base score
8.6HIGH
EPSS probability
0.48%
Higher than 40 percent of all CVEs
CISA KEV
Not listed
CVSS metricWhat it means
Attack vector (AV:N)Network: reachable remotely
Attack complexity (AC:L)Low complexity
Privileges required (PR:N)No privileges required
User interaction (UI:N)No user interaction
Scope (S:C)Scope changed: impact spreads beyond the component
Confidentiality (C:N)No confidentiality impact
Integrity (I:H)High integrity impact
Availability (A:N)No availability impact

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

About Owasp Modsecurity

CVE-2026-52747 affects Owasp Modsecurity, a product from Owasp. Before acting, confirm where Owasp Modsecurity runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.

What the flaw is

In plain terms: ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 3.0.16, the multipart/form-data request body parser in libmodsecurity silently removes embedded line breaks from non-file form-field values before exporting them to ARGS and ARGS_POST because src/request_body_processor/multipart.cc overwrites reserved bytes in m_reserve instead of appending the current buffer. This creates a parser differential between ModSecurity and backend applications that preserve line breaks in form fields, allowing rules that inspect ARGS or ARGS_POST to miss payloads whose dangerous syntax depends on a line break. This issue is fixed in version 3.0.16.

Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Affected versions and timeline

FieldDetail
ProductOwasp Modsecurity
Affected versionsModsecurity before 3.0.16
PublishedJul 10, 2026
Last modifiedJul 14, 2026
Added to CISA KEVNot listed
Assigning CNAsecurity-advisories@github.com

How to detect it

  • Inventory every instance of Owasp Modsecurity and record the running version against the affected range above.
  • Check external attack surface scans for internet facing instances of the component.
  • Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
  • Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.

How to fix it

  • Apply the fixed version of Owasp Modsecurity named in the vendor advisory.
  • If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
  • Rescan after the change to prove the exposure is gone, then close the ticket.

CTEM action plan

CTEM stageWhat to do for this CVE
ScopeAdd every business service that depends on Owasp Modsecurity to the current CTEM cycle.
DiscoverFind all instances, including shadow and cloud deployments, and record versions and exposure.
PrioritizeRank using EPSS and CVSS together with asset exposure and business impact.
ValidateConfirm the flaw is reachable and exploitable in your environment and that compensating controls work.
MobilizeAssign the fix to the asset owner with a due date matched to the priority, then verify closure.

CWE References

Technical References

Frequently asked questions

CVE-2026-52747 is a high severity security vulnerability in Owasp Modsecurity with a CVSS score of 8.6. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

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