CVE-2024-4027 Red Hat CVE debrief

Who should care

Organizations using Undertow-based applications should prioritize patching this vulnerability to prevent potential DoS attacks. Security teams and administrators responsible for maintaining web applications should be aware of this vulnerability and take necessary actions to mitigate the risk. Additionally, developers using Undertow in their applications should review their code to ensure it is not vulnerable to this issue.

Technical summary

The vulnerability in Undertow occurs when servlets use a method that calls HttpServletRequestImpl.getParameterNames(). This can cause an OutOfMemoryError when the client sends a request with large parameter names, leading to a remote denial-of-service (DoS) attack. The issue has a CVSS score of 7.5 and is considered high-severity. The vulnerability is caused by the lack of proper handling of large parameter names in the HttpServletRequestImpl.getParameterNames() method.

Defensive priority

High priority should be given to patching this vulnerability, as it can be exploited by an unauthorized user to cause a remote denial-of-service (DoS) attack. Security teams and administrators should prioritize patching this vulnerability to prevent potential DoS attacks.

Recommended defensive actions

• Apply the patch provided by the vendor to fix the vulnerability.
• Review and update application code to ensure it is not vulnerable to this issue.
• Implement additional security measures, such as monitoring and incident response planning, to mitigate the risk of a potential DoS attack.
• Conduct regular security audits and vulnerability assessments to identify and address potential vulnerabilities.
• Consider implementing compensating controls, such as rate limiting or IP blocking, to mitigate the risk of a potential DoS attack.

Evidence notes

The CVE-2024-4027 vulnerability was published on January 30, 2026, and last modified on June 30, 2026. The vulnerability has a CVSS score of 7.5 and is considered high-severity. The issue occurs when servlets use a method that calls HttpServletRequestImpl.getParameterNames(), which can cause an OutOfMemoryError when the client sends a request with large parameter names.

Official resources