CVE-2026-15565
Undertow: undertow-websockets: undertow: pre-auth dos on websocket endpoint with @serverendpoint class with any @onmessage method
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.
INFO
Published Date :
Aug. 11, 2026, 9:17 a.m.
Last Modified :
Aug. 11, 2026, 9:17 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-15565
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 53f830b8-0a3f-465b-8143-3b8a9948e749 | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update Undertow to the latest version.
- Review WebSocket endpoint security configurations.
- Apply necessary patches provided by the vendor.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-15565.
| URL | Resource |
|---|---|
| https://access.redhat.com/security/cve/CVE-2026-15565 | |
| https://bugzilla.redhat.com/show_bug.cgi?id=2490628 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-15565 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-15565
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-15565 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-15565 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Aug. 11, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:/a:redhat:camel_spring_boot:4'], 'vendor': 'Red Hat', 'product': 'Red Hat build of Apache Camel for Spring Boot 4', 'packageName': 'undertow-websockets-jsr', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:jboss_data_grid:8'], 'vendor': 'Red Hat', 'product': 'Red Hat Data Grid 8', 'packageName': 'undertow-websockets-jsr', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:jboss_fuse:7'], 'vendor': 'Red Hat', 'product': 'Red Hat Fuse 7', 'packageName': 'undertow-websockets-jsr', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unknown'}, {'cpes': ['cpe:/a:redhat:jboss_enterprise_application_platform:7'], 'vendor': 'Red Hat', 'product': 'Red Hat JBoss Enterprise Application Platform 7', 'packageName': 'undertow-websockets-jsr', 'collectionURL': 'https://access.redhat.com/jbossnetwork/restricted/listSoftware.html', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:jboss_enterprise_application_platform:8'], 'vendor': 'Red Hat', 'product': 'Red Hat JBoss Enterprise Application Platform 8', 'packageName': 'undertow-websockets-jsr', 'collectionURL': 'https://access.redhat.com/jbossnetwork/restricted/listSoftware.html', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:jbosseapxp'], 'vendor': 'Red Hat', 'product': 'Red Hat JBoss Enterprise Application Platform Expansion Pack', 'packageName': 'undertow-websockets-jsr', 'collectionURL': 'https://access.redhat.com/jbossnetwork/restricted/listSoftware.html', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:red_hat_single_sign_on:7'], 'vendor': 'Red Hat', 'product': 'Red Hat Single Sign-On 7', 'packageName': 'undertow-websockets-jsr', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unknown'}] 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-120 Added Reference https://access.redhat.com/security/cve/CVE-2026-15565 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2490628