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CVE-2021-42717

Published: Dec 7, 2021Updated: Jul 3, 2025 Sources: CVE List NVD BDUCWE-674
NVD MITRE
7.5CVSSHIGH
EPSS Score
3.2%
Top 13.5%
CISA KEV
Not in KEV
Exploits
1 Known
Remediation
Patch Available

Description

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-674

Affected Products

modsecurityowasp
Mixed
Networking Infrastructure / firewall
modsecuritytrustwave
Mixed
Security Products / vuln-mgmt-scanner
nginx modsecurity waff5
On-prem
Networking Infrastructure / load-balancer-proxy
debian linuxdebian
On-premOS
Operating Systems / linux-distro
http serveroracle
On-premWeb App
Web & CMS Plugins
owasposs-projectUSNetworking Infrastructureaka owasp modsecurity core rule set, modsecurity, modsecurity-crs
trustwavecommercialUSSecurity Products
f5commercialUSNetworking Infrastructure
debianoss-projectGBOperating Systemsaka debian gnu/linux
oraclecommercialUSDatabasesaka oracle corp.
and 4 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

1 exploit source identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available
Workaround Available

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://lists.debian.org/debian-lts-announce/2022/05/msg00042.html
lists.debian.org
https://www.debian.org/security/2021/dsa-5023
debian.org
https://www.oracle.com/security-alerts/cpuapr2022.html
oracle.com
and 4 more references View all →

Timeline

Published
Dec 7, 2021
Last Updated
Jul 3, 2025

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