Denial of service in ModSecurity



Published: 2021-12-19
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-42717
CWE-ID CWE-674
Exploitation vector Network
Public exploit N/A
Vulnerable software
Subscribe 		ModSecurity
Server applications / IDS/IPS systems, Firewalls and proxy servers

Vendor Trustwave

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Uncontrolled Recursion

EUVDB-ID: #VU59052

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-42717

CWE-ID: CWE-674 - Uncontrolled Recursion

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to uncontrolled recursion when processing excessively nested JSON objects. A remote attacker can send a specially crafted HTTP request and consume all available worker processes and CPU resources.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

ModSecurity: 2.8.0 - 3.0.5

External links

http://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-vulnerability-in-json-parsing-cve-2021-42717/


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.



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