HIGHCVSS 7.5EPSS 2.3%

CVE-2025-9784

CVE-2025-9784 updated by NVD

Published: 2025-09-02
Modified: 2026-11-05
EPSS percentile: 83%
Sources: github-advisory, nvd

Summary

A flaw was found in Undertow where malformed client requests can trigger server-side stream resets without triggering abuse counters. This issue, referred to as the "MadeYouReset" attack, allows malicious clients to induce excessive server workload by repeatedly causing server-side stream aborts. While not a protocol bug, this highlights a common implementation weakness that can be exploited to cause a denial of service (DoS).

Affected packages

Ecosystem	Package	Affected versions	Fixed versions
Maven	io.undertow:undertow-core	—	2.2.38.Final, 2.3.20.Final

Remediation: Upgrade to 2.2.38.Final or later.

References

https://nvd.nist.gov/vuln/detail/CVE-2025-9784

Includes data from the GitHub Advisory Database, licensed under CC-BY 4.0.

Includes data from the National Vulnerability Database (NIST). NVD data is in the public domain; this page is not endorsed by NIST.

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EPSS scores provided by the FIRST.org Exploit Prediction Scoring System.