High severity7.5NVD Advisory· Published Dec 7, 2021· Updated Jun 17, 2026
CVE-2021-42717
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.
Affected products
16cpe:2.3:a:oracle:http_server:12.2.1.3.0:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:a:oracle:http_server:12.2.1.3.0:*:*:*:*:*:*:*
- cpe:2.3:a:oracle:http_server:12.2.1.4.0:*:*:*:*:*:*:*
- cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*
cpe:2.3:a:owasp:modsecurity:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:a:owasp:modsecurity:*:*:*:*:*:*:*:*range: >=3.0.0,<3.0.6
- cpe:2.3:a:trustwave:modsecurity:*:*:*:*:*:*:*:*range: >=2.0.0,<2.9.5
- ModSecurity/ModSecuritydescription
- Range: 3.x through 3.0.5, 2.8.0 through 2.9.4
- osv-coords6 versionspkg:bitnami/modsecuritypkg:bitnami/modsecurity2pkg:rpm/opensuse/modsecurity&distro=openSUSE%20Leap%2015.4pkg:rpm/opensuse/modsecurity&distro=openSUSE%20Leap%2015.5pkg:rpm/suse/modsecurity&distro=SUSE%20Package%20Hub%2015%20SP4pkg:rpm/suse/modsecurity&distro=SUSE%20Package%20Hub%2015%20SP5
>= 2.0.0, < 2.9.5+ 5 more
- (no CPE)range: >= 2.0.0, < 2.9.5
- (no CPE)range: >= 2.0.0, < 2.9.5
- (no CPE)range: < 3.0.10-bp154.2.3.1
- (no CPE)range: < 3.0.10-bp155.3.3.1
- (no CPE)range: < 3.0.10-bp154.2.3.1
- (no CPE)range: < 3.0.10-bp155.3.3.1
Patches
Vulnerability mechanics
References
4- www.oracle.com/security-alerts/cpuapr2022.htmlnvdPatchThird Party Advisory
- www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-vulnerability-in-json-parsing-cve-2021-42717/nvdExploitMitigationVendor Advisory
- lists.debian.org/debian-lts-announce/2022/05/msg00042.htmlnvdMailing ListThird Party Advisory
- www.debian.org/security/2021/dsa-5023nvdThird Party Advisory
News mentions
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