{"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":"2026-05-15T12:04:21.307223066Z","published":"2021-12-07T22:15:06.950Z","related":["openSUSE-SU-2023:0257-1","openSUSE-SU-2023:0269-1","openSUSE-SU-2024:12118-1"],"database_specific":{"unresolved_ranges":[{"cpes":["cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*","cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*","cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*"],"extracted_events":[{"last_affected":"9.0"},{"last_affected":"10.0"},{"last_affected":"11.0"}],"source":"CPE_FIELD","vendor_product":"debian:debian_linux"},{"cpes":["cpe:2.3:a:f5:nginx_modsecurity_waf:r24:*:*:*:*:*:*:*","cpe:2.3:a:f5:nginx_modsecurity_waf:r25:*:*:*:*:*:*:*"],"extracted_events":[{"last_affected":"r24"},{"last_affected":"r25"}],"source":"CPE_FIELD","vendor_product":"f5:nginx_modsecurity_waf"},{"cpes":["cpe:2.3:a:oracle:http_server:12.2.1.3.0:*:*:*:*:*:*:*","cpe:2.3:a:oracle:http_server:12.2.1.4.0:*:*:*:*:*:*:*"],"extracted_events":[{"last_affected":"12.2.1.3.0"},{"last_affected":"12.2.1.4.0"}],"source":"CPE_FIELD","vendor_product":"oracle:http_server"},{"cpes":["cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*"],"extracted_events":[{"last_affected":"8.8"}],"source":"CPE_FIELD","vendor_product":"oracle:zfs_storage_appliance_kit"}]},"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/"}],"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"}]}