ModSecurity 3.x through 3.0.5 mishandles excessively nested JSON objects. Crafted JSON objects with nesting tens-of-thousands deep could result in the web server being unable to service legitimate requests. Even a moderately large (e.g., 300KB) HTTP request can occupy one of the limited NGINX worker processes for minutes and consume almost all of the available CPU on the machine. Modsecurity 2 is similarly vulnerable: the affected versions include 2.8.0 through 2.9.4.

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-3031-1 modsecurity-apache security update
Debian DSA Debian DSA DSA-5023-1 modsecurity-apache security update
EUVD EUVD EUVD-2021-29677 ModSecurity 3.x through 3.0.5 mishandles excessively nested JSON objects. Crafted JSON objects with nesting tens-of-thousands deep could result in the web server being unable to service legitimate requests. Even a moderately large (e.g., 300KB) HTTP request can occupy one of the limited NGINX worker processes for minutes and consume almost all of the available CPU on the machine. Modsecurity 2 is similarly vulnerable: the affected versions include 2.8.0 through 2.9.4.
Ubuntu USN Ubuntu USN USN-6370-1 ModSecurity vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 16 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.02045}

epss

{'score': 0.02101}


Thu, 03 Jul 2025 21:15:00 +0000

Type Values Removed Values Added
First Time appeared Owasp
Owasp modsecurity
CPEs cpe:2.3:a:owasp:modsecurity:*:*:*:*:*:*:*:*
Vendors & Products Owasp
Owasp modsecurity

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2024-08-04T03:38:49.325Z

Reserved: 2021-10-19T00:00:00

Link: CVE-2021-42717

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2021-12-07T22:15:06.950

Modified: 2025-07-03T20:59:18.650

Link: CVE-2021-42717

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses