vulntracker.iovulntracker.io
© 2026 vulntracker.io

CVE-2021-42717

HIGH
7.5
CVSS Score
Published: December 7, 2021 at 09:08 PM UTC
Updated: June 17, 2026 at 04:10 AM UTC
6 products affected across 5 vendorsDebian LinuxZfs Storage Appliance KitHTTP Server

Using N/A by N/A?

Get instant alerts when new vulnerabilities affect N/A - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Start FreeSign In
Severity
HIGH7.5
Exploit prediction
EPSS 3%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Debian Linux· Debiandrupal
95%
10.011.09.0
nginx Modsecurity Waf· F5
95%
r24r25
HTTP Server· Oracle
95%
12.2.1.3.012.2.1.4.0
Zfs Storage Appliance Kit· Oracle
95%
8.8
Modsecurity· Owasp
95%
3.0.0 ≤ v < 3.0.6
Affected range stops below 3.0.6, so it looks safe — our inference, not a vendor statement
Modsecurity· Trustwave
95%
2.0.0 ≤ v < 2.9.5
Affected range stops below 2.9.5, so it looks safe — our inference, not a vendor statement

References (4)

Mailing Listx_refsource_MLISTThird Party Advisory
Source: [email protected]
https://lists.debian.org/debian-lts-announce/2022/05/msg00042.html
Vendor Advisoryx_refsource_DEBIANThird Party Advisory
Source: [email protected]
https://www.debian.org/security/2021/dsa-5023
x_refsource_MISCPatchThird Party Advisory
Source: [email protected]
https://www.oracle.com/security-alerts/cpuapr2022.html
x_refsource_MISCExploitMitigationVendor Advisory
Source: [email protected]
https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-vulnerability-in-json-parsing-cve-2021-42717/

CVSS

7.5HIGH[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-674

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Create accountSign in
Free plan, no card