CVE-2026-76166
Modcluster-core: mod_cluster advertise listener: unauthenticated dos via crafted multicast datagram
Description
A flaw was found in mod_cluster's AdvertiseListenerImpl (org.jboss.modcluster core module). A single crafted UDP multicast datagram with a valid HTTP status line and a "Server:" header but without the "Date:", "Digest:", and "Sequence:" headers triggers a NullPointerException in verifyDigest() that is not caught by the worker thread's exception handler. This causes the advertise listener thread to terminate permanently. The failure is silent (isListening() continues to return true) and persists until the node is restarted. The crash occurs before the AdvertiseSecurityKey comparison, so deployments with a configured security key are still affected.
INFO
Published Date :
Aug. 19, 2026, 10:16 a.m.
Last Modified :
Aug. 19, 2026, 10:16 a.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-76166
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 | MEDIUM | 53f830b8-0a3f-465b-8143-3b8a9948e749 | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update mod_cluster to a patched version.
- Apply vendor-provided security updates.
- Restart the affected node.
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-2026-76166.
| URL | Resource |
|---|---|
| https://access.redhat.com/security/cve/CVE-2026-76166 | |
| https://bugzilla.redhat.com/show_bug.cgi?id=2510883 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-76166 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-2026-76166
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-2026-76166 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-76166 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. 19, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:/a:redhat:jboss_enterprise_application_platform:7'], 'vendor': 'Red Hat', 'product': 'Red Hat JBoss Enterprise Application Platform 7', 'packageName': 'mod_cluster-core', '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': 'mod_cluster-core', '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': 'mod_cluster-core', 'collectionURL': 'https://access.redhat.com/jbossnetwork/restricted/listSoftware.html', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:jboss_enterprise_web_server:5'], 'vendor': 'Red Hat', 'product': 'Red Hat JBoss Web Server 5', 'packageName': 'mod_cluster-core', 'collectionURL': 'https://access.redhat.com/jbossnetwork/restricted/listSoftware.html', 'defaultStatus': 'unknown'}, {'cpes': ['cpe:/a:redhat:jboss_enterprise_web_server:6'], 'vendor': 'Red Hat', 'product': 'Red Hat JBoss Web Server 6', 'packageName': 'mod_cluster-core', 'collectionURL': 'https://access.redhat.com/jbossnetwork/restricted/listSoftware.html', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:jboss_enterprise_web_server:7'], 'vendor': 'Red Hat', 'product': 'Red Hat JBoss Web Server 7', 'packageName': 'mod_cluster-core', 'collectionURL': 'https://access.redhat.com/jbossnetwork/restricted/listSoftware.html', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:red_hat_single_sign_on:7'], 'vendor': 'Red Hat', 'product': 'Red Hat Single Sign-On 7', 'packageName': 'mod_cluster-core', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}] Added Description A flaw was found in mod_cluster's AdvertiseListenerImpl (org.jboss.modcluster core module). A single crafted UDP multicast datagram with a valid HTTP status line and a "Server:" header but without the "Date:", "Digest:", and "Sequence:" headers triggers a NullPointerException in verifyDigest() that is not caught by the worker thread's exception handler. This causes the advertise listener thread to terminate permanently. The failure is silent (isListening() continues to return true) and persists until the node is restarted. The crash occurs before the AdvertiseSecurityKey comparison, so deployments with a configured security key are still affected. Added CVSS V3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Added CWE CWE-476 Added Reference https://access.redhat.com/security/cve/CVE-2026-76166 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2510883