cve/2021/CVE-2021-42717.md

CVE-2021-42717

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.

POC

Reference

• https://www.oracle.com/security-alerts/cpuapr2022.html

Github

• https://github.com/EkamSinghWalia/Detection-and-Mitigation-script-for-CVE-2021-42717
• https://github.com/nomi-sec/PoC-in-GitHub