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CVE-2025-9784
September 02, 2025
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
io.undertow:undertow-core (JAVA):
Affected version(s) >=2.3.0.Alpha1 <2.3.20.Final
Fix Suggestion:
Update to version 2.3.20.Final
io.undertow:undertow-core (JAVA):
Affected version(s) >=1.0.0.Alpha1 <2.2.38.Final
Fix Suggestion:
Update to version 2.2.38.Final
Additional Notes
The description of this vulnerability differs from MITRE.
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CVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Improper Resource Shutdown or Release
Allocation of Resources Without Limits or Throttling
EPSS
Base Score:
0.43