Bugzilla – Bug 1195450
VUL-0: CVE-2021-42717: apache2-mod_security2: crafted JSON objects with nesting could result in the web server being unable to service legitimate requests
Last modified: 2022-02-03 12:28:40 UTC
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.
The following codestreams include the JSON code, but do not contain the fix  (included in v2.9.5 and v3.0.6):
However, the original report  specifies that if modsecurity is built without yajl, the package is not vulnerable. I do not see the `--with-yajl` flag in the .spec file for these codestreams.
@Danilo, could you please confirm whether we build with or without JSON support? Thanks.
I can confirm that we build apache2-mod-security2 without support for yajl library.
Thanks for the quick response Danilo. Closing the issue, as builds without JSON support are not affected.