CVE-2023-38199: Owasp Coreruleset

Critical severity, CVSS 9.8. EPSS: 0.7% chance of exploitation in the next 30 days.

coreruleset (aka OWASP ModSecurity Core Rule Set) through 3.3.4 does not detect multiple Content-Type request headers on some platforms. This might allow attackers to bypass a WAF with a crafted payload, aka "Content-Type confusion" between the WAF and the backend application. This occurs when the web application relies on only the last Content-Type header. Other platforms may reject the additional Content-Type header or merge conflicting headers, leading to detection as a malformed header.

Affected products

• Owasp Coreruleset: up to and including 3.3.4

Published 2023-07-13. Last modified 2026-06-17.