CVE-2021-42717: High severity modsecurity vulnerability
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 Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is CVE-2021-42717?
CVE-2021-42717 is a vulnerability in ModSecurity 3.x through 3.0.5 that mishandles excessively nested JSON objects.
How does CVE-2021-42717 affect ModSecurity?
CVE-2021-42717 can result in the web server being unable to service legitimate requests due to crafted JSON objects with excessive nesting.
What is the severity of CVE-2021-42717?
The severity of CVE-2021-42717 is moderate.
How can I mitigate CVE-2021-42717?
To mitigate CVE-2021-42717, update ModSecurity to version 2.9.2-1ubuntu0.1~ or apply the appropriate remedy provided by your distribution.
Where can I find more information about CVE-2021-42717?
More information about CVE-2021-42717 can be found on the CVE details page and the ModSecurity GitHub issue page.