CVE-2025-9784 | Undertow: undertow madeyoureset http/2 ddos vulnerability

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).

Published: 2025-09-02 Last update: 2026-03-18 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2025-9784 is rated Moderate Risk (60.2/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.23%). Mandatory action: Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-9784

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-19 1.70% 2.23% +0.53%
2 2026-05-08 1.55% 1.70% +0.15%
3 2026-03-29 1.55%

Full EPSS history (23 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-9784

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 3.6 [email protected]

Weakness enumeration for CVE-2025-9784

GitHub Security Advisory for CVE-2025-9784

GHSA-95h4-w6j8-2rp8 · Severity: high · Ecosystem: maven — Undertow MadeYouReset HTTP/2 DDoS Vulnerability

OS Trackers for CVE-2025-9784

vendor priority summary link
debian not yet assigned CVE-2025-9784 not yet assigned priority: Debian including 1 source packages (undertow), 2 status rows across 2 suites (forky, sid): resolved 2. https://security-tracker.debian.org/tracker/CVE-2025-9784
redhat high https://access.redhat.com/security/cve/CVE-2025-9784
ubuntu medium CVE-2025-9784 medium priority: Ubuntu including 2 source packages (resteasy, undertow), 15 status rows across 8 suites (bionic, focal, jammy, noble, plucky, questing, upstream, xenial): needs-triage 13, ignored 2. https://ubuntu.com/security/CVE-2025-9784

Affected software / configurations for CVE-2025-9784

Vendor Product Version Raw CPE
redhat build_of_apache_camel_for_spring_boot cpe:2.3:a:redhat:build_of_apache_camel_for_spring_boot:-:*:*:*:*:*:*:*
redhat fuse 7.0.0 cpe:2.3:a:redhat:fuse:7.0.0:*:*:*:*:*:*:*
redhat jboss_enterprise_application_platform 7.0.0 cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.0.0:*:*:*:*:*:*:*
redhat jboss_enterprise_application_platform 8.0.0 cpe:2.3:a:redhat:jboss_enterprise_application_platform:8.0.0:*:*:*:*:*:*:*
redhat jboss_enterprise_application_platform_expansion_pack cpe:2.3:a:redhat:jboss_enterprise_application_platform_expansion_pack:-:*:*:*:*:*:*:*
redhat process_automation 7.0 cpe:2.3:a:redhat:process_automation:7.0:*:*:*:*:*:*:*
redhat single_sign-on 7.0 cpe:2.3:a:redhat:single_sign-on:7.0:*:*:*:*:*:*:*
redhat undertow cpe:2.3:a:redhat:undertow:-:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:-:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*

References for CVE-2025-9784

URL Tags
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-2026:3889
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/security/cve/CVE-2025-9784 Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2392306 Issue Tracking
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
https://www.kb.cert.org/vuls/id/767506
cvelogic Threat Intelligence