An issue was discovered in OWASP ModSecurity Core Rule Set (CRS) through 3.1.0. /rules/REQUEST-942-APPLICATION-ATTACK-SQLI.conf allows remote attackers to cause a denial of service (ReDOS) by entering a specially crafted string with nested repetition operators.
https://github.com/SpiderLabs/owasp-modsecurity-crs/issues/1359
https://github.com/SpiderLabs/owasp-modsecurity-crs/blob/v3.1/dev/CHANGES
https://coreruleset.org/20190627/announcement-owasp-modsecurity-core-rule-set-version-3-1-1/