Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2021-42717

Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
07/12/2021
Last modified:
03/07/2025

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.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.50 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x
7.50
Severity 3.x
HIGH
Vector 2.0
AV:N/AC:L/Au:N/C:N/I:N/A:P CVSS v2.0 Severity and Metrics:

Base Score: 5.00 MEDIUM
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P

Attack Vector (AV): Network
Attack Complexity (AC): Low
Authentication (Au): None
Confidentiality (C): None
Integrity (I): None
Availability (A): Physical

Base Score 2.0
5.00
Severity 2.0
MEDIUM

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:owasp:modsecurity:*:*:*:*:*:*:*:* 3.0.0 (including) 3.0.6 (excluding)
cpe:2.3:a:trustwave:modsecurity:*:*:*:*:*:*:*:* 2.0.0 (including) 2.9.5 (excluding)
cpe:2.3:a:f5:nginx_modsecurity_waf:r24:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_modsecurity_waf:r25:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:http_server:12.2.1.3.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:http_server:12.2.1.4.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools