CVE-2025-9784 Undertow
| Affected software | Undertow |
|---|---|
| Severity | 7.5 High CVSS 3.1 |
| Fixed in | 2.2.38.Final, 2.3.20.Final |
| Weakness | CWE-770 |
| Published | 2 Sep 2025 |
| Updated | 4 Nov 2026 |
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).
CWE-404
Exploitation status
No public exploit
No exploit has been reported in the sources we check. The 1 repository below are public GitHub repositories with fewer than 5 stars.
Exploitation status
- CISA KEV not listed
- VulnCheck KEV not listed
- CISA Vulnrichment exploitation: none
- Indexed PoC 1 indexed, none at 5+ stars
- EPSS 2.3% chance in 30 days
| Index | Artifact | Stars | First seen |
|---|---|---|---|
| GitHub PoC | drackyjr/CVE-2025-9784 | 2 | 2025-09-02 |
Waratek protection
Within Waratek scope. In the sources we check, nobody has published exploit code for this CVE or reported it being exploited.
A public code fix exists: undertow-io/undertow #1778.
- Protection none
- Action unverified
- Review automated Upstream data
- Record active
| Decided by | Exploit code for this candidate, published in a reviewed catalogue or a GitHub repository with 5 or more stars, or in use per CISA or VulnCheck; not only a CISA verdict, a forecast, or nothing at all |
|---|---|
| Finding | This CVE is not listed in CISA KEV or VulnCheck KEV, CISA Vulnrichment records no active exploitation, no reviewed exploit catalogue carries an entry for it, and no GitHub PoC repository for it has 5 or more stars. Nobody has published exploit code worth tracing, so it is not a candidate for a rule ahead of the ones where somebody has; an upstream fix path does exist, so the remediation half of the candidacy still holds. This is a statement about what has been published, not about whether the defect is reachable or serious. |
| Candidate fix | https://github.com/undertow-io/undertow/pull/1778 : a pull request: the change under review |
Affected software and releases
Maven packages
Affected and fixed versions, from OSV.dev| Package | Introduced | Fixed | Last affected |
|---|---|---|---|
io.undertow:undertow-core |
0 | 2.2.38.Final |
unbounded |
io.undertow:undertow-core |
2.3.0.Alpha1 | 2.3.20.Final |
unbounded |
Products and versions
9 products, 12 version entries| Source | Vendor | Product | Scheme | Affected versions |
|---|---|---|---|---|
| osv | io.undertow | undertow-core | generic | ＜ 2.2.38 · ≥ 2.3.0 and ＜ 2.3.20 |
| nvd | redhat | build of apache camel for spring boot | generic | any version |
| nvd | redhat | enterprise linux | generic | 8.0 · 9.0 |
| nvd | redhat | fuse | generic | 7.0.0 |
| nvd | redhat | jboss enterprise application platform | generic | 7.0.0 · 8.0.0 |
| nvd | redhat | jboss enterprise application platform expansion pack | generic | any version |
| nvd | redhat | process automation | generic | 7.0 |
| nvd | redhat | single sign-on | generic | 7.0 |
| nvd | redhat | undertow | generic | any version |
References
Timeline
Timeline
| Published | 2025-09-02 | By the CVE Program. |
|---|---|---|
| NVD record modified | 2026-11-04 | NVD's own last-modified date for this record. |