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).
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 2.3% (30-day exploitation probability)+12
- Technical severity (high)+6
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Maven Io.undertow:undertow-core: fixed in version 2.2.38.Final — github.com (GitHub Security Advisories)
- Maven Io.undertow:undertow-core: fixed in version 2.3.20.Final — github.com (GitHub Security Advisories)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Red Hat Build Of Apache Camel For Spring Boot, Red Hat Enterprise Linux, Red Hat Fuse…).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Red Hat | Build Of Apache Camel For Spring Boot | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux | version 9.0version 8.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Fuse | version 7.0.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Jboss Enterprise Application Platform | version 7.0.0version 8.0.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Jboss Enterprise Application Platform Expansion Pack | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Jboss Enterprise Application Platform Expansion Pack | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Process Automation | version 7.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Red Hat Data Grid 8 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Fuse 7 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7.3 EUS for RHEL 7 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 8 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 9 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7.4.24 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 8 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 9 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8.1.3 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Process Automation 7 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Single Sign-On 7.6 for RHEL 7 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Single Sign-On 7.6 for RHEL 8 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Single Sign-On 7.6 for RHEL 9 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | RHEL-8 based Middleware Containers | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Single Sign-on | version 7.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Undertow | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Maven | Io.undertow:undertow-core | ≥ 2.3.0.Alpha1 and < 2.3.20.Final< 2.2.38.Final | Vulnerable | GitHub Security Advisories |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.5 | CVSS 3.1 | High | 3.9 | 3.6 | secalert@redhat.com via NIST National Vulnerability Database |
| 7.5 | CVSS 3.1 | High | — | — | GitHub, Inc. via GitHub Security Advisories |
| 7.5 | CVSS 3.1 | High | — | — | redhat via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: secalert@redhat.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
CWE-770 · Allocation of Resources Without Limits or Throttling
EPSS over time FIRST
Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 2.33%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Track CPU/memory spikes and availability drops correlated with request patterns.
Timeline
What happened to this CVE, newest first.
- 2026
- Fix documented
- Affected products added · maven/io.undertow:undertow-core
- Affected products removed · 1
- Affected products added · red hat/red hat jboss enterprise application platform 8.1.3
- Affected products added · red hat/red hat jboss enterprise application platform 7.1 eus for rhel 7, red hat/red hat jboss enterprise application p
- SSVC assessment updated
- Record published
- CVSS changed · 7.5
- Source status changed · → Modified
- Record created in this database
- 2025
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× References added · Oct 14, 2026 – Oct 14, 2026
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
31 on the record
- access.redhat.com/security/cve/CVE-2025-9784
- access.redhat.com/errata/RHSA-2026:33371
- access.redhat.com/errata/RHSA-2026:76130
- issues.redhat.com/browse/UNDERTOW-2598
- access.redhat.com/errata/RHSA-2026:0386
- github.com/undertow-io/undertow/pull/1778
- access.redhat.com/errata/RHSA-2026:0384
- access.redhat.com/errata/RHSA-2025:23143
- www.kb.cert.org/vuls/id/767506
- access.redhat.com/errata/RHSA-2026:4917
- access.redhat.com/errata/RHSA-2026:76134
- access.redhat.com/errata/RHSA-2026:76132
- github.com/advisories/GHSA-95h4-w6j8-2rp8
- nvd.nist.gov/vuln/detail/CVE-2025-9784
- access.redhat.com/errata/RHSA-2026:4915
- access.redhat.com/errata/RHSA-2026:33372
- access.redhat.com/errata/RHSA-2026:76128
- bugzilla.redhat.com/show_bug.cgi
- access.redhat.com/errata/RHSA-2026:4916
- access.redhat.com/errata/RHSA-2026:3889
- github.com/undertow-io/undertow/releases/tag/2.2.38.Final
- access.redhat.com/errata/RHSA-2026:3892
- github.com/undertow-io/undertow/pull/1803
- access.redhat.com/errata/RHSA-2026:0383
- access.redhat.com/errata/RHSA-2026:4924
- kb.cert.org/vuls/id/767506
- github.com/undertow-io/undertow/pull/1805
- access.redhat.com/errata/RHSA-2026:3891
- github.com/undertow-io/undertow/pull/1804
- github.com/undertow-io/undertow/pull/1802
- access.redhat.com/errata/RHSA-2026:76129
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-84823 Org.wildfly.core: wildfly: path traversal in take-snapshot discloses the server configuration to the monitor role 16h
- Medium CVE-2026-104045 Sssd: sssd: denial of service via race condition in autofs responder 9d
- Medium CVE-2026-104046 Sssd: sssd: denial of service via incomplete identity provider authentication requests 9d
- High CVE-2026-104048 Sssd: sssd: authorization bypass via cross-domain username collision in hbac evaluation 9d
- Medium CVE-2026-104047 Sssd: sssd: information disclosure via query injection in entra id lookups 9d
- High CVE-2026-102559 Libsoup: libsoup: heap buffer overflow during websocket client-frame masking 16d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2025-9784 is "Undertow: undertow madeyoureset http/2 ddos vulnerability", rated High. It affects Build Of Apache Camel For Spring Boot (Red Hat); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. EPSS 2.33% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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