Description
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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | modsecurity-crs | 3.3.5-1 | — |
| Debian 13 | modsecurity-crs | 3.3.5-1 | — |
| Debian 12 | modsecurity-crs | 3.3.4-1+deb12u2 | — |
| Debian 11 | modsecurity-crs | 3.3.4-1~deb11u2 | DLA-4488-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | modsecurity-crs | No fix yet | — |
| Ubuntu 26.04 LTS | modsecurity-crs | No fix yet | — |
| Ubuntu 25.10 | modsecurity-crs | No fix yet | — |
| Ubuntu 24.04 LTS | modsecurity-crs | No fix yet | — |
| Ubuntu 22.04 LTS | modsecurity-crs | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | modsecurity-crs | No fix yet | — |
| Ubuntu 18.04 LTS | modsecurity-crs | No fix yet | — |
| Ubuntu 16.04 LTS | modsecurity-crs | No fix yet | — |
Advisories 3
- DLA-4488-1 modsecurity-crs - security update Debian Security (DSA / DLA) · Feb 22, 2026
- ICSA-24-046-15 Siemens SINEC NMS CISA ICS & IT advisories · Mar 12, 2024
- SSA-943925 SSA-943925: Multiple Vulnerabilities in SINEC NMS before V2.0 SP1 Siemens ProductCERT · Mar 12, 2024