{"id":"CVE-2021-42717","details":"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.","aliases":["BIT-modsecurity-2021-42717","BIT-modsecurity2-2021-42717"],"modified":"2026-04-16T04:34:44.199075949Z","published":"2021-12-07T22:15:06.950Z","related":["openSUSE-SU-2023:0257-1","openSUSE-SU-2023:0269-1","openSUSE-SU-2024:12118-1"],"references":[{"type":"ADVISORY","url":"https://lists.debian.org/debian-lts-announce/2022/05/msg00042.html"},{"type":"ADVISORY","url":"https://www.debian.org/security/2021/dsa-5023"},{"type":"FIX","url":"https://www.oracle.com/security-alerts/cpuapr2022.html"},{"type":"EVIDENCE","url":"https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-vulnerability-in-json-parsing-cve-2021-42717/"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/owasp-modsecurity/modsecurity","events":[{"introduced":"c1cd668acb820824e791ba802396c60900eae9c1"},{"fixed":"c3d7f4b560797a052681dcffb97a22bb906487cd"},{"introduced":"0"},{"fixed":"860299971df990610943c2ff18c70e7e5716db8b"}],"database_specific":{"versions":[{"introduced":"3.0.0"},{"fixed":"3.0.6"},{"introduced":"2.0.0"},{"fixed":"2.9.5"}]}}],"versions":["v2.7.4","v2.9.0","v2.9.0-rc1","v2.9.0-rc2","v2.9.1","v2.9.1-rc1","v2.9.2","v2.9.3","v2.9.4","v3.0.0","v3.0.1","v3.0.2","v3.0.3","v3.0.4","v3.0.5"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-42717.json","unresolved_ranges":[{"events":[{"introduced":"0"},{"last_affected":"r24"}]},{"events":[{"introduced":"0"},{"last_affected":"r25"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0"}]},{"events":[{"introduced":"0"},{"last_affected":"10.0"}]},{"events":[{"introduced":"0"},{"last_affected":"11.0"}]},{"events":[{"introduced":"0"},{"last_affected":"12.2.1.3.0"}]},{"events":[{"introduced":"0"},{"last_affected":"12.2.1.4.0"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8"}]}]}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}