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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat JBoss Enterprise Application Platform 8.1.6 | — | — |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8 | — | — |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9 | — | — |
| Red Hat | Red Hat build of Apache Camel for Spring Boot 4 | — | — |
| Red Hat | Red Hat build of Apache Camel - HawtIO 4 | — | — |
| Red Hat | Red Hat Data Grid 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat Fuse 7 | — | — |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | — | — |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8 | — | — |
| Red Hat | Red Hat JBoss Enterprise Application Platform Expansion Pack | — | — |
| Red Hat | Red Hat Process Automation 7 | — | — |
| Red Hat | Red Hat Single Sign-On 7 | — | — |
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 | undertow | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | undertow | No fix yet | — |
| Ubuntu 26.04 LTS | undertow | No fix yet | — |
| Ubuntu 25.10 | undertow | No fix yet | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | undertow | No fix yet | — |
| Ubuntu Pro 22.04 LTS | undertow | No fix yet | — |
| Ubuntu Pro 20.04 LTS | undertow | No fix yet | — |
| Ubuntu Pro 18.04 LTS | undertow | No fix yet | — |
| Ubuntu Pro 16.04 LTS | undertow | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat JBoss EAP 8 | eap8-activemq-artemis +14 | 2.40.0-7.redhat_00015.1.el8eap | RHSA-2026:25125 |
| Red Hat JBoss EAP 8 | eap8-eap-product-conf-parent +1 | 801.6.1-1.GA_redhat_00001.1.el8eap | RHSA-2026:25125 |
| Red Hat JBoss EAP 8 | eap8-undertow | 2.3.24-3.SP2_redhat_00001.1.el8eap | RHSA-2026:25125 |
| Red Hat JBoss EAP 8 | eap8-wildfly +3 | 8.1.6-7.GA_redhat_00010.1.el8eap | RHSA-2026:25125 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Maven | io.undertow:undertow-core | < 2.2.40.Final | 2.2.40.Final | GHSA-vqqj-9cmv-hx43 |
| Maven | io.undertow:undertow-core | >= 2.3.0.Final, < 2.3.25.Final | 2.3.25.Final | GHSA-vqqj-9cmv-hx43 |
Advisories 4
- WID-SEC-2026-4090 Oracle Communications: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
- NCSC-2026-0444 Kwetsbaarheden verholpen in Oracle Communications NCSC-NL (Netherlands) · Oct 21, 2026
- RHSA-2026:25125 Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 8.1.6 security update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- WID-SEC-2026-0907 Red Hat Undertow: Mehrere Schwachstellen ermöglichen Umgehung von Sicherheitsmaßnahmen BSI CERT-Bund (WID) · Jun 10, 2026
References
- RHSA-2026:25125 vendor-advisory
- RHSA-2026:25126 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-28369 vdb-entry
- RHBZ#2443262 issue-tracking