Undertow: undertow-websockets: undertow: pre-auth dos on websocket endpoint with @serverendpoint class with any @onmessage method
Summary
| CVE | CVE-2026-15565 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-11 09:17:13 UTC |
| Updated | 2026-08-11 09:17:13 UTC |
| Description | A flaw was found in Undertow. A remote attacker can cause Out of Memory on websockets endpoint without authentication on any @ServerEndpoint class that has any @OnMessage method. This allows an attacker to cause Denial of Service attack without authentication and using only a standard WebSocket handshake. |
Risk And Classification
Primary CVSS: v3.1 7.5 HIGH from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Problem Types: CWE-120 | CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | CNA | CVSS | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Red Hat Build Of Apache Camel For Spring Boot 4 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Data Grid 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Fuse 7 | Not specified | Not specified |
| CNA | Red Hat | Red Hat JBoss Enterprise Application Platform 7 | Not specified | Not specified |
| CNA | Red Hat | Red Hat JBoss Enterprise Application Platform 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat JBoss Enterprise Application Platform Expansion Pack | Not specified | Not specified |
| CNA | Red Hat | Red Hat Single Sign-On 7 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| access.redhat.com/security/cve/CVE-2026-15565 | [email protected] | access.redhat.com | |
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-06-19T00:58:08.395Z | Reported to Red Hat. |
| CNA | 2026-08-11T05:55:42.770Z | Made public. |
Workarounds
CNA: Option 1 — Server-wide configuration to disable websockets handshake: <!-- Remove <websockets/> from standalone.xml servlet-container --> <servlet-container name="default"> <jsp-config/> <!-- <websockets/> ← remove this line entirely --> </servlet-container> isWebsocketsEnabled() returns false → no WebSocket upgrade accepted for any deployment. Option 2 — Per-application configuration to disable websockets handshake: <!-- WEB-INF/jboss-web.xml inside the WAR --> <jboss-web> <enable-websockets>false</enable-websockets> </jboss-web> Only that specific WAR's @ServerEndpoint classes are not registered.