CVE-2026-15565

Undertow: undertow-websockets: undertow: pre-auth dos on websocket endpoint with @serverendpoint class with any @onmessage method

Published Aug 11, 2026 CVSS 3.1 · 7.5 High EPSS 1.0% KEV · Not listed
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.

Remediation

Vendor Workaround

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.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:/a:redhat:jboss_enterprise_application_platform_els:7.4::el8
cpe:/a:redhat:jboss_enterprise_application_platform_els:7.4::el9
Type Values Removed Values Added
CPEs cpe:/a:redhat:jboss_enterprise_application_platform:7
Type Values Removed Values Added
CPEs cpe:/a:redhat:jboss_enterprise_application_platform:7
Type Values Removed Values Added
CPEs cpe:/a:redhat:jboss_enterprise_application_platform:7
cpe:/a:redhat:jboss_enterprise_application_platform:7.4
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:jboss_enterprise_application_platform:8 cpe:/a:redhat:jboss_enterprise_application_platform:8.1::el10
cpe:/a:redhat:jboss_enterprise_application_platform:8.1::el8
cpe:/a:redhat:jboss_enterprise_application_platform:8.1::el9
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:jboss_enterprise_application_platform_els:7.4::el9
References
Type Values Removed Values Added
First Time appeared Redhat jboss Enterprise Application Platform Els
CPEs cpe:/a:redhat:jboss_enterprise_application_platform:7
cpe:/a:redhat:jboss_enterprise_application_platform:7.4::el7
cpe:/a:redhat:jboss_enterprise_application_platform_els:7.4::el7
cpe:/a:redhat:jboss_enterprise_application_platform_els:7.4::el8
Vendors & Products Redhat jboss Enterprise Application Platform Els
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:jboss_enterprise_application_platform:7
Type Values Removed Values Added
CPEs cpe:/a:redhat:jboss_enterprise_application_platform:7 cpe:/a:redhat:jboss_enterprise_application_platform:7.4::el7
References
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Redhat build Of Apache Camel For Spring Boot
Redhat data Grid 8
Redhat fuse
Redhat jboss Enterprise Application Platform Expansion Pack
Redhat single Sign On
Redhat undertow
Vendors & Products Redhat build Of Apache Camel For Spring Boot
Redhat data Grid 8
Redhat fuse
Redhat jboss Enterprise Application Platform Expansion Pack
Redhat single Sign On
Redhat undertow
Type Values Removed Values Added
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.
Title Undertow: undertow-websockets: undertow: pre-auth dos on websocket endpoint with @serverendpoint class with any @onmessage method
First Time appeared Redhat
Redhat camel Spring Boot
Redhat jboss Data Grid
Redhat jboss Enterprise Application Platform
Redhat jboss Fuse
Redhat jbosseapxp
Redhat red Hat Single Sign On
Weaknesses CWE-120
CPEs cpe:/a:redhat:camel_spring_boot:4
cpe:/a:redhat:jboss_data_grid:8
cpe:/a:redhat:jboss_enterprise_application_platform:7
cpe:/a:redhat:jboss_enterprise_application_platform:8
cpe:/a:redhat:jboss_fuse:7
cpe:/a:redhat:jbosseapxp
cpe:/a:redhat:red_hat_single_sign_on:7
Vendors & Products Redhat
Redhat camel Spring Boot
Redhat jboss Data Grid
Redhat jboss Enterprise Application Platform
Redhat jboss Fuse
Redhat jbosseapxp
Redhat red Hat Single Sign On
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}