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Full vulnerability report · 2025
CVE-2025-9784High confidence

Undertow: undertow madeyoureset http/2 ddos vulnerability

Unknown · Unknown

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

2 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · esm-appsresteasyUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · esm-appsundertowUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2025-9784 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityundertow: Undertow MadeYouReset HTTP/2 DDoS Vulnerability
6 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • undertow-core as a component of Red Hat Data Grid 8
  • undertow-core as a component of Red Hat Fuse 7
  • undertow-core as a component of Red Hat JBoss Enterprise Application Platform 7
  • org.jboss.eap-jboss-eap-xp as a component of Red Hat JBoss Enterprise Application Platform Expansion Pack
  • undertow-core as a component of Red Hat Process Automation 7
  • undertow-core as a component of Red Hat Single Sign-On 7
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).
Remediation
Before applying this update, ensure all previously released errata relevant to your system have been applied. Also, back up your existing installation, including all applications, configuration files, databases and database settings. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2025-26388

No EUVD known-exploited evidence

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).

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
7.5 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

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).

What

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).

Why

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

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).

Why

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Allocation of Resources Without Limits or Throttling → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-770 ↗

CWE-770: Allocation of Resources Without Limits or Throttling. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of serviceCWE-770
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2025-26388Official EUVD mapping

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).

Official EUVD record
BSI · German · WID-SEC-W-2026-0054Red Hat JBoss Enterprise Application Platform (Undertow): Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Red Hat JBoss Enterprise Application Platform ausnutzen, um einen Denial of Service Zustand herbeizuführen, Daten zu manipulieren und um weitere Angriffe wie Cache-Poisoning und Session-Hijacking durchzuführen.

Official advisory
BSI · German · WID-SEC-W-2025-2204NetApp ActiveIQ Unified Manager (Undertow): Schwachstelle ermöglicht Denial of Service

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in NetApp ActiveIQ Unified Manager und NetApp OnCommand Unified Manager ausnutzen, um einen Denial of Service Angriff durchzuführen.

Official advisory
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
undertow-core as a component of Red Hat Data Grid 8; undertow-core as a component of Red Hat Fuse 7; undertow-core as a component of Red Hat JBoss Enterprise Application Platform 7; org.jboss.eap-jboss-eap-xp as a component of Red Hat JBoss Enterprise Application Platform Expansion Pack; undertow-core as a component of Red Hat Process Automation 7; undertow-core as a component of Red Hat Single Sign-On 7
Fixed
eap7-undertow-0:1.4.18-21.SP19_redhat_00001.1.ep7.el7.noarch as a component of Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7 Server; eap7-undertow-0:1.4.18-21.SP19_redhat_00001.1.ep7.el7.src as a component of Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7 Server; eap7-undertow-0:2.0.41-8.SP9_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss Enterprise Application Platform 7.3 EUS for RHEL 7 Server; eap7-undertow-0:2.0.41-8.SP9_redhat_00001.1.el7eap.src as a component of Red Hat JBoss Enterprise Application Platform 7.3 EUS for RHEL 7 Server; eap7-undertow-0:2.2.39-1.Final_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-undertow-0:2.2.39-1.Final_redhat_00001.1.el7eap.src as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-wildfly-0:7.4.24-4.GA_redhat_00002.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-wildfly-0:7.4.24-4.GA_redhat_00002.1.el7eap.src as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-wildfly-java-jdk11-0:7.4.24-4.GA_redhat_00002.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-wildfly-java-jdk8-0:7.4.24-4.GA_redhat_00002.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-wildfly-javadocs-0:7.4.24-4.GA_redhat_00002.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-wildfly-modules-0:7.4.24-4.GA_redhat_00002.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-undertow-0:2.2.39-1.Final_redhat_00001.1.el8eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 8; eap7-undertow-0:2.2.39-1.Final_redhat_00001.1.el8eap.src as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 8; eap7-wildfly-0:7.4.24-4.GA_redhat_00002.1.el8eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 8; eap7-wildfly-0:7.4.24-4.GA_redhat_00002.1.el8eap.src as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 8; eap7-wildfly-java-jdk11-0:7.4.24-4.GA_redhat_00002.1.el8eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 8; eap7-wildfly-java-jdk17-0:7.4.24-4.GA_redhat_00002.1.el8eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 8; eap7-wildfly-java-jdk8-0:7.4.24-4.GA_redhat_00002.1.el8eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 8; eap7-wildfly-javadocs-0:7.4.24-4.GA_redhat_00002.1.el8eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 8; eap7-wildfly-modules-0:7.4.24-4.GA_redhat_00002.1.el8eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 8; eap8-bouncycastle-0:1.83.0-1.redhat_00001.1.el8eap.noarch as a component of Red Hat JBoss EAP 8.0 for RHEL 8; eap8-bouncycastle-0:1.83.0-1.redhat_00001.1.el8eap.src as a component of Red Hat JBoss EAP 8.0 for RHEL 8; eap8-bouncycastle-jmail-0:1.83.0-1.redhat_00001.1.el8eap.noarch as a component of Red Hat JBoss EAP 8.0 for RHEL 8; eap8-bouncycastle-pg-0:1.83.0-1.redhat_00001.1.el8eap.noarch as a component of Red Hat JBoss EAP 8.0 for RHEL 8; eap8-bouncycastle-pkix-0:1.83.0-1.redhat_00001.1.el8eap.noarch as a component of Red Hat JBoss EAP 8.0 for RHEL 8; eap8-bouncycastle-prov-0:1.83.0-1.redhat_00001.1.el8eap.noarch as a component of Red Hat JBoss EAP 8.0 for RHEL 8; eap8-bouncycastle-util-0:1.83.0-1.redhat_00001.1.el8eap.noarch as a component of Red Hat JBoss EAP 8.0 for RHEL 8; eap8-codemodel-0:4.0.6-1.redhat_00001.1.el8eap.noarch as a component of Red Hat JBoss EAP 8.0 for RHEL 8; eap8-guava-0:33.0.0-2.jre_redhat_00003.1.el8eap.noarch as a component of Red Hat JBoss EAP 8.0 for RHEL 8; and 174 more
Action
Before applying this update, ensure all previously released errata relevant to your system have been applied. Also, back up your existing installation, including all applications, configuration files, databases and database settings. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 2 Sept 2025 · Last source change 4 Sept 2026, 19:51 UTC · CWE-770 · Allocation of Resources Without Limits or Throttling

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-26388
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment

Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates →
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    < 2.2.38.Final · Fixed: 0:1.4.18-21.SP19_redhat_00001.1.ep7.el7 < *; 0:2.0.41-8.SP9_redhat_00001.1.el7eap < *; 0:2.2.39-1.Final_redhat_00001.1.el7eap < *; 0:7.4.24-4.GA_redhat_00002.1.el7eap < *; 0:2.2.39-1.Final_redhat_00001.1.el8eap < *
    After
    < 2.2.38.Final · Fixed: 0:1.4.18-21.SP19_redhat_00001.1.ep7.el7 < *; 0:2.0.41-8.SP9_redhat_00001.1.el7eap < *; 2.2.39.Final-redhat-00001 < *; 0:2.2.39-1.Final_redhat_00001.1.el7eap < *; 0:7.4.24-4.GA_redhat_00002.1.el7eap < *; 0:2.2.39-1.Final_redhat_00001.1.el8eap < *
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2025-26388↗Vendor advisory↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2025-9784 · cve.blacktree.nl