Debian 11 modsecurity-crs Moderate Content-Type Attack Bypass DLA-4488-1

CVE-2023-38199

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.

CVE-2026-21876

The current rule 922110 has a bug when processing multipart requests
with multiple parts. When the first rule in a chain iterates over a
collection (like `MULTIPART_PART_HEADERS`), the capture variables
(`TX:0`, `TX:1`) get overwritten with each iteration. Only the last
captured value is available to the chained rule, which means malicious
charsets in earlier parts can be missed if a later part has a legitimate
charset.