CVE-2025-9784GHSA-95h4-w6j8-2rp8
io.undertow:undertow-core: Undertow MadeYouReset HTTP/2 DDoS Vulnerability
io.undertow:undertow-coremavenLibraries & packages
CVSS
7.5HighExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)2.33%Chance of exploitation activity in the next 30 days, higher than 83% of CVEs. Scored 23 Oct 2026FIRST EPSS
What fixes it
- 2.2.38.Finalio.undertow:undertow-core, mavenGitHub
<dependency><groupId>io.undertow</groupId><artifactId>undertow-core</artifactId><version>2.2.38.Final</version></dependency> - 2.3.20.Finalio.undertow:undertow-core, mavenGitHub
<dependency><groupId>io.undertow</groupId><artifactId>undertow-core</artifactId><version>2.3.20.Final</version></dependency> - 2.2.38.FinalCVE List
- 2.2.38.Finalio.undertow:undertow-core, MavenOSV
<dependency><groupId>io.undertow</groupId><artifactId>undertow-core</artifactId><version>2.2.38.Final</version></dependency> - 2.3.20.Finalio.undertow:undertow-core, MavenOSV
<dependency><groupId>io.undertow</groupId><artifactId>undertow-core</artifactId><version>2.3.20.Final</version></dependency>
A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.
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).
Text from CVE List
Affected versions 115
- io.undertow:undertow-core, maven< 2.2.38.FinalGitHub
- io.undertow:undertow-core, maven>= 2.3.0.Alpha1, < 2.3.20.FinalGitHub
- Productaffected: all versions before 2.2.38.FinalCVE List
- Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7unaffected: 0:1.4.18-21.SP19_redhat_00001.1.ep7.el7 and laterCVE List
- Red Hat JBoss Enterprise Application Platform 7.3 EUS for RHEL 7unaffected: 0:2.0.41-8.SP9_redhat_00001.1.el7eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 7.4.24unaffected: 2.2.39.Final-redhat-00001 and laterCVE List
- Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7unaffected: 0:2.2.39-1.Final_redhat_00001.1.el7eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7unaffected: 0:7.4.24-4.GA_redhat_00002.1.el7eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 8unaffected: 0:2.2.39-1.Final_redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 8unaffected: 0:7.4.24-4.GA_redhat_00002.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 9unaffected: 0:2.2.39-1.Final_redhat_00001.1.el9eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 9unaffected: 0:7.4.24-4.GA_redhat_00002.1.el9eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 8unaffected: 0:1.83.0-1.redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 8unaffected: 0:33.0.0-2.jre_redhat_00003.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 8unaffected: 0:4.0.6-1.redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 8unaffected: 0:1.0.0-3.redhat_00009.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 8unaffected: 0:2.0.2-1.Final_redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 8unaffected: 0:2.3.23-1.SP3_redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 9unaffected: 0:1.83.0-1.redhat_00001.1.el9eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 9unaffected: 0:33.0.0-2.jre_redhat_00003.1.el9eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 9unaffected: 0:4.0.6-1.redhat_00001.1.el9eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 9unaffected: 0:1.0.0-3.redhat_00009.1.el9eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 9unaffected: 0:2.0.2-1.Final_redhat_00001.1.el9eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 9unaffected: 0:2.3.23-1.SP3_redhat_00001.1.el9eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1.3unaffected: 2.3.20.SP4-redhat-00001 and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:4.0.10-1.redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:1.82.0-1.redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:801.3.0-1.GA_redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:1.0.1-3.redhat_00003.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:6.6.36-1.Final_redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:4.0.2-1.Final_redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:2.5.0-1.redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:2.3.20-2.SP4_redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:8.1.3-4.GA_redhat_00006.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:5.0.12-1.Final_redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:2.6.6-1.Final_redhat_00001.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8unaffected: 0:8.1.1-4.GA_redhat_00007.1.el8eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9unaffected: 0:4.0.10-1.redhat_00001.1.el9eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9unaffected: 0:1.82.0-1.redhat_00001.1.el9eap and laterCVE List
- Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9unaffected: 0:801.3.0-1.GA_redhat_00001.1.el9eap and laterCVE List
- io.undertow:undertow-core, Mavenfrom first release, fixed in 2.2.38.FinalOSV
- io.undertow:undertow-core, Maven1.0.0.Alpha1OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha10OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha11OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha12OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha13OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha14OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha15OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha16OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha17OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha18OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha19OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha2OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha20OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha21OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha22OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha3OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha4OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha5OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha6OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha7OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha8OSV
- io.undertow:undertow-core, Maven1.0.0.Alpha9OSV
- io.undertow:undertow-core, Maven1.0.0.Beta1OSV
- io.undertow:undertow-core, Maven1.0.0.Beta10OSV
- io.undertow:undertow-core, Maven1.0.0.Beta11OSV
- io.undertow:undertow-core, Maven1.0.0.Beta12OSV
- io.undertow:undertow-core, Maven1.0.0.Beta13OSV
- io.undertow:undertow-core, Maven1.0.0.Beta14OSV
- io.undertow:undertow-core, Maven1.0.0.Beta15OSV
- io.undertow:undertow-core, Maven1.0.0.Beta16OSV
- io.undertow:undertow-core, Maven1.0.0.Beta17OSV
- io.undertow:undertow-core, Maven1.0.0.Beta18OSV
- io.undertow:undertow-core, Maven1.0.0.Beta19OSV
- io.undertow:undertow-core, Maven1.0.0.Beta2OSV
- io.undertow:undertow-core, Maven1.0.0.Beta20OSV
- io.undertow:undertow-core, Maven1.0.0.Beta21OSV
- io.undertow:undertow-core, Maven1.0.0.Beta22OSV
- io.undertow:undertow-core, Maven1.0.0.Beta23OSV
- io.undertow:undertow-core, Maven1.0.0.Beta24OSV
- io.undertow:undertow-core, Maven1.0.0.Beta25OSV
- io.undertow:undertow-core, Maven1.0.0.Beta26OSV
- io.undertow:undertow-core, Maven1.0.0.Beta27OSV
- io.undertow:undertow-core, Maven1.0.0.Beta28OSV
- io.undertow:undertow-core, Maven1.0.0.Beta29OSV
- io.undertow:undertow-core, Maven1.0.0.Beta3OSV
- io.undertow:undertow-core, Maven1.0.0.Beta30OSV
- io.undertow:undertow-core, Maven1.0.0.Beta31OSV
- io.undertow:undertow-core, Maven1.0.0.Beta32OSV
- io.undertow:undertow-core, Maven1.0.0.Beta33OSV
- io.undertow:undertow-core, Maven1.0.0.Beta4OSV
- io.undertow:undertow-core, Mavenfrom 2.3.0.Alpha1, fixed in 2.3.20.FinalOSV
- io.undertow:undertow-core, Maven2.3.0.Alpha1OSV
- io.undertow:undertow-core, Maven2.3.0.Alpha2OSV
- io.undertow:undertow-core, Maven2.3.0.Beta1OSV
- io.undertow:undertow-core, Maven2.3.0.FinalOSV
- io.undertow:undertow-core, Maven2.3.1.FinalOSV
- io.undertow:undertow-core, Maven2.3.10.FinalOSV
- io.undertow:undertow-core, Maven2.3.11.FinalOSV
- io.undertow:undertow-core, Maven2.3.12.FinalOSV
- io.undertow:undertow-core, Maven2.3.13.FinalOSV
- io.undertow:undertow-core, Maven2.3.14.FinalOSV
- io.undertow:undertow-core, Maven2.3.15.FinalOSV
- io.undertow:undertow-core, Maven2.3.16.FinalOSV
- io.undertow:undertow-core, Maven2.3.17.FinalOSV
- io.undertow:undertow-core, Maven2.3.18.FinalOSV
- io.undertow:undertow-core, Maven2.3.19.FinalOSV
- io.undertow:undertow-core, Maven2.3.2.FinalOSV
- io.undertow:undertow-core, Maven2.3.3.FinalOSV
- io.undertow:undertow-core, Maven2.3.4.FinalOSV
- io.undertow:undertow-core, Maven2.3.5.FinalOSV
- io.undertow:undertow-core, Maven2.3.6.FinalOSV
- io.undertow:undertow-core, Maven2.3.7.FinalOSV
- io.undertow:undertow-core, Maven2.3.8.FinalOSV
- io.undertow:undertow-core, Maven2.3.9.FinalOSV
References 31
- github.com/undertow-io/undertow/releases/tag/2.2.38.FinalFixvia CVE List
- access.redhat.com/security/cve/CVE-2025-9784Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2025:23143Advisoryvia CVE List
- kb.cert.org/vuls/id/767506Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:0384Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:0386Advisoryvia CVE List
- kb.cert.org/vuls/id/767506Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:0383Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:3892Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:3891Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:3889Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:4924Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:4917Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:4916Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:4915Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:33372Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:33371Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:76134Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:76132Advisoryvia CVE List
- github.com/advisories/GHSA-95h4-w6j8-2rp8Advisoryvia GitHub
- access.redhat.com/errata/RHSA-2026:76128Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:76129Advisoryvia CVE List
- access.redhat.com/errata/RHSA-2026:76130Advisoryvia CVE List
- nvd.nist.gov/vuln/detail/CVE-2025-9784Referencevia GitHub
- bugzilla.redhat.com/show_bug.cgi?id=2392306Referencevia CVE List
- github.com/undertow-io/undertow/pull/1778Referencevia CVE List
- issues.redhat.com/browse/UNDERTOW-2598Referencevia CVE List
- github.com/undertow-io/undertow/pull/1802Referencevia GitHub
- github.com/undertow-io/undertow/pull/1803Referencevia GitHub
- github.com/undertow-io/undertow/pull/1804Referencevia GitHub
- github.com/undertow-io/undertow/pull/1805Referencevia GitHub