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Public proof of conceptFix available

CVE-2025-9784

Undertow: undertow madeyoureset http/2 ddos vulnerability

A public proof of concept exists; no exploitation attested.

  • Published2025-09-02
  • WeaknessCWE-404 · CWE-770

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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).

Timeline

dates in UTC
  1. 2025-09-0213:37CVE publishedCNA
  2. 2025-09-0214:15CVE publishedNVD

Versions per branch

NVD · OSV
Redhat enterprise linux
BranchAffectedFixed in
8.0= 8.0no fix published
9.0= 9.0no fix published
Redhat jboss enterprise application platform
BranchAffectedFixed in
7.0= 7.0.0no fix published
8.0= 8.0.0no fix published
undertow-core
BranchAffectedFixed in
2.3≥ 2.3.0.Alpha1, < 2.3.20.Final2.3.20.Final
2.2< 2.2.38.Final2.2.38.Final

6 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA67 products

As redhat, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

61 more products in the CVE record.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-04

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • eap7-apache-cxfRed Hat:jboss_enterprise_application_platform_eus:7.3::el7all versions · fixed in 0:3.4.10-4.SP2_redhat_00004.1.el7eapand 3 other packages
  • eap7-apache-cxfRed Hat:jboss_enterprise_application_platform_eus:7.1::el7all versions · fixed in 0:3.1.16-7.redhat_00007.1.ep7.el7and 3 other packages
  • eap7-apache-cxfRed Hat:jboss_enterprise_application_platform_els:7.4::el9all versions · fixed in 0:3.5.11-1.SP1_redhat_00001.1.el9eapand 3 other packages
  • eap7-apache-cxfRed Hat:jboss_enterprise_application_platform_els:7.4::el8all versions · fixed in 0:3.5.11-1.SP1_redhat_00001.1.el8eapand 3 other packages
  • eap7-apache-cxfRed Hat:jboss_enterprise_application_platform_els:7.4::el7all versions · fixed in 0:3.5.11-1.SP1_redhat_00001.1.el7eapand 3 other packages
  • eap7-eclipse-jgitRed Hat:jboss_enterprise_application_platform_els:7.4::el9all versions · fixed in 0:5.13.5.202508271544-2.r_redhat_00001.1.el9eap
  • eap7-eclipse-jgitRed Hat:jboss_enterprise_application_platform_els:7.4::el8all versions · fixed in 0:5.13.5.202508271544-2.r_redhat_00001.1.el8eap
  • eap7-eclipse-jgitRed Hat:jboss_enterprise_application_platform_els:7.4::el7all versions · fixed in 0:5.13.5.202508271544-2.r_redhat_00001.1.el7eap

72 more package ranges on OSV.dev

Vendor advisories

  • CVE-2025-9784 Red Hat Product Security217 products fixed · 5 known affected

    undertow: Undertow MadeYouReset HTTP/2 DDoS Vulnerability

    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 · +2 more

  • RHSA-2026:76128 Red Hat Product Security3 products fixed

    Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update on RHEL 7

  • RHSA-2026:76130 Red Hat Product Security3 products fixed

    Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update on RHEL 9

  • RHSA-2026:76129 Red Hat Product Security3 products fixed

    Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update on RHEL 8

  • RHSA-2026:76134 Red Hat Product Security3 products fixed

    Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 for OpenShift image security update

  • RHSA-2026:76132 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update

13 more advisories

Full record on NVD

Fix

  1. Vendor fix Red Hat Product Security RHSA-2026:76128 · 3 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
  2. Vendor fix Red Hat Product Security RHSA-2026:76134 · 3 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
  3. Vendor fix Red Hat Product Security RHSA-2026:76132 · 1 productBefore applying the update, back up your existing installation, including all applications, configuration files, databases and database settings, and so on. The References section of this erratum contains a download link (you must log in to download the update).
  4. Vendor fix Red Hat Product Security RHSA-2026:33371 · 2 productsBefore 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…
  5. Vendor fix Red Hat Product Security RHSA-2026:4924 · 1 productBefore applying the update, make sure 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://acce…
  6. Workaround from the vendor Red Hat Product Security RHSA-2026:76128 · 3 productsNo mitigation is currently available that meets Red Hat Product Security’s standards for usability, deployment, applicability, or stability.

Advisories and patches

Detection

read 2026-11-01 01:02 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2025-09-02
Last Modified
2026-11-04
NVD status
Modified
GitHub Advisory
GHSA-95h4-w6j8-2rp8

Frequently asked questions

What is CVE-2025-9784?

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).

Is CVE-2025-9784 actively exploited?

Active exploitation of CVE-2025-9784 has not been confirmed. Its EPSS score was 2.3% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2025-9784?

CVE-2025-9784 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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