CVE-2021-42717

Severity Score

7.5

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

ModSecurity versiones 3.x hasta 3.0.5, maneja inapropiadamente los objetos JSON excesivamente anidados. Los objetos JSON diseñados con un anidamiento de decenas de miles de metros de profundidad podían hacer que el servidor web no pudiera atender peticiones legítimas. Incluso una petición HTTP moderadamente grande (por ejemplo, 300KB) puede ocupar uno de los limitados procesos de trabajo de NGINX durante minutos y consumir casi toda la CPU disponible en la máquina. Modsecurity 2 es igualmente vulnerable: las versiones afectadas incluyen la 2.8.0 hasta la 2.9.4

*Credits: N/A

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-10-19 CVE Reserved
2021-12-07 CVE Published
2022-11-20 First Exploit
2024-08-04 CVE Updated
2024-08-22 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-674: Uncontrolled Recursion

CAPEC

References (5)

URL	Tag	Source
https://lists.debian.org/debian-lts-announce/2022/05/msg00042.html	Mailing List

URL	Date	SRC
https://github.com/EkamSinghWalia/Detection-and-Mitigation-script-for-CVE-2021-42717	2022-11-20
https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-vulnerability-in-json-parsing-cve-2021-42717	2024-08-04

URL	Date	SRC
https://www.oracle.com/security-alerts/cpuapr2022.html	2022-09-03

URL	Date	SRC
https://www.debian.org/security/2021/dsa-5023	2022-09-03

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Trustwave Search vendor "Trustwave"		Modsecurity Search vendor "Trustwave" for product "Modsecurity"				>= 2.0.0 < 2.9.5 Search vendor "Trustwave" for product "Modsecurity" and version " >= 2.0.0 < 2.9.5"		-		Affected
Trustwave Search vendor "Trustwave"		Modsecurity Search vendor "Trustwave" for product "Modsecurity"				>= 3.0.0 < 3.0.6 Search vendor "Trustwave" for product "Modsecurity" and version " >= 3.0.0 < 3.0.6"		-		Affected
F5 Search vendor "F5"		Nginx Modsecurity Waf Search vendor "F5" for product "Nginx Modsecurity Waf"				r24 Search vendor "F5" for product "Nginx Modsecurity Waf" and version "r24"		-		Affected
F5 Search vendor "F5"		Nginx Modsecurity Waf Search vendor "F5" for product "Nginx Modsecurity Waf"				r25 Search vendor "F5" for product "Nginx Modsecurity Waf" and version "r25"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				9.0 Search vendor "Debian" for product "Debian Linux" and version "9.0"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				10.0 Search vendor "Debian" for product "Debian Linux" and version "10.0"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				11.0 Search vendor "Debian" for product "Debian Linux" and version "11.0"		-		Affected
Oracle Search vendor "Oracle"		Http Server Search vendor "Oracle" for product "Http Server"				12.2.1.3.0 Search vendor "Oracle" for product "Http Server" and version "12.2.1.3.0"		-		Affected
Oracle Search vendor "Oracle"		Http Server Search vendor "Oracle" for product "Http Server"				12.2.1.4.0 Search vendor "Oracle" for product "Http Server" and version "12.2.1.4.0"		-		Affected
Oracle Search vendor "Oracle"		Zfs Storage Appliance Kit Search vendor "Oracle" for product "Zfs Storage Appliance Kit"				8.8 Search vendor "Oracle" for product "Zfs Storage Appliance Kit" and version "8.8"		-		Affected