Bug 2443262 (CVE-2026-28369) - CVE-2026-28369 undertow: Undertow: Request Smuggling via Malformed HTTP Request Headers
Summary: CVE-2026-28369 undertow: Undertow: Request Smuggling via Malformed HTTP Reque...
Keywords:
Status: NEW
Alias: CVE-2026-28369
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-02-27 04:44 UTC by OSIDB Bzimport
Modified: 2026-07-21 02:45 UTC (History)
59 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:25125 0 None None None 2026-06-10 20:27:12 UTC
Red Hat Product Errata RHSA-2026:25126 0 None None None 2026-06-10 20:25:11 UTC

Description OSIDB Bzimport 2026-02-27 04:44:52 UTC 
When Undertow receives a request in which the first header line begins
with one or more spaces, it strips them before processing the request.
This is usable as a request smuggling primitive.

The HTTP RFCs state that when a field-line begins with a space or tab,
it is permissible to concatenate it into the previous field-line's
value. This is referred to as `obs-fold` in the RFCs. However, it is
always invalid to obs-fold on the first line, since there is no
previous field-line to concatenate into. Thus, the message should be
rejected.
Comment 2 errata-xmlrpc 2026-06-10 20:25:08 UTC 
This issue has been addressed in the following products:

  Red Hat JBoss Enterprise Application Platform 8.1

Via RHSA-2026:25126 https://access.redhat.com/errata/RHSA-2026:25126
Comment 3 errata-xmlrpc 2026-06-10 20:27:08 UTC 
This issue has been addressed in the following products:

  Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9
  Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8

Via RHSA-2026:25125 https://access.redhat.com/errata/RHSA-2026:25125
Comment 4 Helen Grace 2026-07-21 02:43:15 UTC 
(In reply to errata-xmlrpc from comment #3)
> This issue has been addressed in the following products:
> 
>   Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9
>   Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8
> 
> Via RHSA-2026:25125 https://access.redhat.com/errata/RHSA-2026:25125https://freewebgames.io/

Thanks!
Comment 5 Helen Grace 2026-07-21 02:45:01 UTC 
(In reply to Helen Grace from comment #4)
> (In reply to errata-xmlrpc from comment #3)
> > This issue has been addressed in the following products:
> > 
> >   Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9
> >   Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8
> > 
> > Via RHSA-2026:25125 https://access.redhat.com/errata/RHSA-2026:25125 https://freewebgames.io/
> 
> Thanks!
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