Summaryinfo

A vulnerability classified as critical has been found in Undertow. This impacts an unknown function of the component Requests Handler. This manipulation causes request smuggling. The identification of this vulnerability is CVE-2026-28368. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as critical was found in Undertow (version now known). Affected by this vulnerability is some unknown processing of the component Requests Handler. The manipulation with an unknown input leads to a request smuggling vulnerability. The CWE definition for the vulnerability is CWE-444. The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

A flaw was found in Undertow. This vulnerability allows a remote attacker to construct specially crafted requests where header names are parsed differently by Undertow compared to upstream proxies. This discrepancy in header interpretation can be exploited to launch request smuggling attacks, potentially bypassing security controls and accessing unauthorized resources.

The advisory is shared at access.redhat.com. This vulnerability is known as CVE-2026-28368 since 02/27/2026. The exploitation appears to be difficult. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 03/30/2026).

The vulnerability scanner Nessus provides a plugin with the ID 304101 (Linux Distros Unpatched Vulnerability : CVE-2026-28368), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Tenable (304101). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• Undertow

License

• free

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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