CVE-2026-28369 — Vulnerability in io.undertow:undertow-parent —...

HIGH

Undertow is Vulnerable to HTTP Request/Response Smuggling

Published March 27, 2026Updated September 10, 2026Source: osv

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.

Advisory Timeline

First published March 27, 2026 (199 days ago).
Last revised September 10, 2026 — 166 days after initial publication.

Affected Packages (1)

Affects 1 ecosystem: maven (1).

Package	Ecosystem	Affected	Fixed In
io.undertow:undertow-parent	maven	1.0.0.Alpha1, 1.0.0.Alpha10, 1.0.0.Alpha11, 1.0.0.Alpha12 (+332 more)	Range-based data available

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CWE-444
View on MITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 8.7 score means for each attack dimension.

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

None

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

References

Frequently Asked Questions

What is CVE-2026-28369?: Undertow is Vulnerable to HTTP Request/Response Smuggling This vulnerability has been assigned a severity rating of HIGH (CVSS score: 8.7/10).
How do I check if my project is affected by CVE-2026-28369?: CVE-2026-28369 affects io.undertow:undertow-parent. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-28369 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score

8.7

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-vqqj-9cmv-hx43

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