CVE-2021-42717
Fixed in a distro release EPSS 3%
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.
Products: owasp modsecurity, trustwave modsecurity, f5 nginx_modsecurity_waf, debian_linux, oracle http_server, oracle zfs_storage_appliance_kit
Distro releases
| Release | Package | Fixed in |
|---|---|---|
| Debian 10 | modsecurity-apache | 2.9.3-1+deb10u1 |
| Debian 11 | modsecurity-apache | 2.9.3-3+deb11u1 |
| Debian 12 | modsecurity | 3.0.6-1 |
| Debian 12 | modsecurity-apache | 2.9.5-1 |
| Debian 13 | modsecurity | 3.0.6-1 |
| Debian 13 | modsecurity-apache | 2.9.5-1 |
| Debian 14 | modsecurity | 3.0.6-1 |
| Debian 14 | modsecurity-apache | 2.9.5-1 |
| Debian 9 | modsecurity-apache | 2.9.1-2+deb9u1 |
| SUSE Package Hub 15 SP4 | modsecurity | 3.0.10-bp154.2.3.1 |
| SUSE Package Hub 15 SP5 | modsecurity | 3.0.10-bp155.3.3.1 |
| Ubuntu 20.04 LTS | modsecurity | no fix |
| Ubuntu 20.04 LTS | modsecurity-apache | 2.9.3-1ubuntu0.1 |
| Ubuntu 22.04 LTS | modsecurity | no fix |
| Ubuntu 24.04 LTS | modsecurity | no fix |
| Ubuntu 25.10 | modsecurity | no fix |
| Ubuntu 26.04 LTS | modsecurity | no fix |
| Ubuntu 26.10 | modsecurity | no fix |
| Ubuntu Pro 14.04 LTS | modsecurity-apache | 2.7.7-2ubuntu0.1~esm1 |
| Ubuntu Pro 16.04 LTS | modsecurity-apache | 2.9.0-1ubuntu0.1~esm1 |
| Ubuntu Pro 18.04 LTS | modsecurity-apache | 2.9.2-1ubuntu0.1~esm1 |
| Ubuntu Pro 22.04 LTS | modsecurity-apache | 2.9.5-1ubuntu0.1~esm1 |
| openSUSE Leap 15.4 | modsecurity | 3.0.10-bp154.2.3.1 |
| openSUSE Leap 15.5 | modsecurity | 3.0.10-bp155.3.3.1 |