CVE-2026-28369 Undertow: undertow: request smuggling via malformed http request headers
Remote attackers can perform HTTP request smuggling via malformed headers in Undertow, bypassing security controls and exposing data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-28369?
CVE-2026-28369 is a high-severity vulnerability in Redhat Enterprise Linux, published on 27 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A flaw was found in Undertow. When Undertow receives an HTTP request where the first header line starts with one or more spaces, it incorrectly processes the request by stripping these leading spaces. This behavior, which violates HTTP standards, can be exploited by a remote attacker to perform request smuggling. Request smuggling allows an attacker to bypass security mechanisms, access restricted information, or manipulate web caches, potentially leading to unauthorized actions or data exposure.
Weakness: CWE-444
Which versions are affected by CVE-2026-28369?
2 open source packages ship an affected version, including io.undertow:undertow-parent. It affects 10 products.
| Package | Affected | Fixed in |
|---|---|---|
io.undertow:undertow-parent Maven | All versions to 2.3.23.Final | None |
io.undertow:undertow-parent Maven | All versions to 2.3.23.Final | None |
Products include Redhat Build of Apache Camel - Hawtio, Redhat Build of Apache Camel for Spring Boot, Redhat Data Grid, Redhat Enterprise Linux, Redhat Fuse, Redhat Jboss Enterprise Application Platform and 4 more.
How do I fix CVE-2026-28369?
Apply the vendor's patch.
Is CVE-2026-28369 being exploited?
There is no known exploitation of CVE-2026-28369 in the wild and no public exploit code.
Other vulnerabilities in Redhat Enterprise Linux
Sources
Also known as DEBIAN-CVE-2026-28369, GHSA-vqqj-9cmv-hx43, UBUNTU-CVE-2026-28369.