CVE-2026-28369

[CVE catalog]

Severity

High · CVSS 8.7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N

Published

Jan 1, 2026, 12:00:00 AM UTC

Source

[NVD] · [CVE record]

EPSS

0.69% · Oct 25, 2026

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. undertow: Undertow: Request Smuggling via Malformed HTTP Request Headers The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.