OutOfMemoryError DoS in Undertow via Large Parameter Names

Publication date: 2026-01-30

Last updated on: 2026-06-30

Assigner: Red Hat, Inc.

Description

A flaw was found in Undertow. Servlets using a method that calls HttpServletRequestImpl.getParameterNames() can cause an OutOfMemoryError when the client sends a request with large parameter names. This issue can be exploited by an unauthorized user to cause a remote denial-of-service (DoS) attack.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-01-30

Last Modified

2026-06-30

Generated

2026-07-06

AI Q&A

2026-01-30

EPSS Evaluated

2026-07-05

NVD

CVE-2024-4027

Affected Vendors & Products

Vendor	Product	Version / Range
unknown_vendor	undertow	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-20	The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

Attack-Flow Graph

Executive Summary

This vulnerability is a flaw in Undertow where servlets that use a method calling HttpServletRequestImpl.getParameterNames() can trigger an OutOfMemoryError if a client sends a request with very large parameter names. This can be exploited remotely by an unauthorized user to cause a denial-of-service (DoS) attack.

Impact Analysis

The vulnerability can impact you by allowing an unauthorized attacker to remotely cause a denial-of-service (DoS) condition on your server, potentially making your application unavailable due to an OutOfMemoryError.

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