A flaw was found in Undertow. A remote attacker can exploit this vulnerability by sending `\r\r\r` as a header block terminator. This can be used for request smuggling with certain proxy servers, such as older versions of Apache Traffic Server and Google Cloud Classic Application Load Balancer, potentially leading to unauthorized access or manipulation of web requests.

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Advisories

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Fixes

Solution

No solution given by the vendor.


Workaround

To mitigate this vulnerability, configure any proxy servers positioned in front of Undertow to strictly validate HTTP header terminations. Ensure that these proxies are configured to reject or normalize non-standard header block terminators, such as `\r\r\r`, before forwarding requests to Undertow. This operational control helps prevent request smuggling attacks by ensuring that only properly formed HTTP requests reach the Undertow server.

History

Fri, 27 Mar 2026 16:45:00 +0000

Type Values Removed Values Added
Description A flaw was found in Undertow. A remote attacker can exploit this vulnerability by sending `\r\r\r` as a header block terminator. This can be used for request smuggling with certain proxy servers, such as older versions of Apache Traffic Server and Google Cloud Classic Application Load Balancer, potentially leading to unauthorized access or manipulation of web requests.
Title Undertow: undertow: request smuggling via `\r\r\r` as a header block terminator
First Time appeared Redhat
Redhat apache Camel Hawtio
Redhat camel Spring Boot
Redhat enterprise Linux
Redhat jboss Data Grid
Redhat jboss Enterprise Application Platform
Redhat jboss Enterprise Bpms Platform
Redhat jboss Fuse
Redhat jbosseapxp
Redhat red Hat Single Sign On
Weaknesses CWE-444
CPEs cpe:/a:redhat:apache_camel_hawtio:4
cpe:/a:redhat:camel_spring_boot:4
cpe:/a:redhat:jboss_data_grid:8
cpe:/a:redhat:jboss_enterprise_application_platform:7
cpe:/a:redhat:jboss_enterprise_application_platform:8
cpe:/a:redhat:jboss_enterprise_bpms_platform:7
cpe:/a:redhat:jboss_fuse:7
cpe:/a:redhat:jbosseapxp
cpe:/a:redhat:red_hat_single_sign_on:7
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat apache Camel Hawtio
Redhat camel Spring Boot
Redhat enterprise Linux
Redhat jboss Data Grid
Redhat jboss Enterprise Application Platform
Redhat jboss Enterprise Bpms Platform
Redhat jboss Fuse
Redhat jbosseapxp
Redhat red Hat Single Sign On
References
Metrics cvssV3_1

{'score': 8.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-03-27T17:00:45.370Z

Reserved: 2026-02-27T04:42:16.439Z

Link: CVE-2026-28367

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-03-27T17:16:27.750

Modified: 2026-03-27T17:16:27.750

Link: CVE-2026-28367

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses