CVE-2026-28369 in Undertow

Summary

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.

Responsible

redhat

Reservation

02/27/2026

Disclosure

03/27/2026

Entries

VulDB provides additional information and datapoints for this CVE:

ID	Vulnerability	CWE	Exp	Cou	CVE
354000	Undertow HTTP Request request smuggling	444	Not defined	Not defined	CVE-2026-28369