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.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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. (CVE-2026-28367)

The remote Redhat Enterprise Linux 8 / 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:25125 advisory.

    Red Hat JBoss Enterprise Application Platform 8 is a platform for Java applications based on the WildFly     application runtime.

    This asynchronous patch is an update for Red Hat JBoss Enterprise Application Platform 8.1. See Release     Notes for information about the most significant bug fixes and enhancements included in this release.

    Security Fix(es):

    * jetty-server: Eclipse Jetty: Denial of Service due to unreleased JDK Inflater from compressed HTTP     requests important (CVE-2026-1605)

    * undertow-core: Undertow: Request Smuggling via Malformed HTTP Request Headers (CVE-2026-28369)

    * undertow-core: Undertow: Request smuggling via inconsistent header parsing (CVE-2026-28368)

    * undertow-core: Undertow: Request smuggling via `\r\r\r` as a header block terminator (CVE-2026-28367)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-28367)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
446635	SCA: security update for io.undertow:undertow-parent (GHSA-3gv6-g396-9v4r)	Tenable Cloud Security	SCA Checks	Local	critical
446635	SCA: security update for io.undertow:undertow-parent (GHSA-3gv6-g396-9v4r)	Tenable Self-Hosted Container Security	SCA Checks	Local	critical
320509	RHEL 8 / 9 : Red Hat JBoss Enterprise Application Platform 8.1.6 (RHSA-2026:25125)	Nessus	Red Hat Local Security Checks	Local	critical
304100	Linux Distros Unpatched Vulnerability : CVE-2026-28367	Nessus	Misc.	Local	critical

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CVE-2026-28367

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Tenable Plugins

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