# Modcluster-core: mod_cluster advertise listener: unauthenticated dos via crafted multicast datagram CVE record · `CVE-2026-76166` - **Identifiers:** `CVE-2026-76166` - **State:** Confirmed - **Severity:** CVSS 4.3 Medium - **Critical:** No - **CNA:** redhat - **Weakness (CWE):** [CWE-476](https://cwe.mitre.org/data/definitions/476.html) - **Tags:** [Memory corruption](https://agentprime.io/advisories/tag/memory-corruption.md) - **Technologies:** [Red Hat JBoss Web Server 7.0.3](https://agentprime.io/advisories/technology/red-hat-jboss-web-server-7-0-3.md) · [Red Hat JBoss Web Server 7.0 on RHEL 10](https://agentprime.io/advisories/technology/red-hat-jboss-web-server-7-0-on-rhel-10.md) · [Red Hat JBoss Web Server 7.0 on RHEL 8](https://agentprime.io/advisories/technology/red-hat-jboss-web-server-7-0-on-rhel-8.md) · [Red Hat JBoss Web Server 7.0 on RHEL 9](https://agentprime.io/advisories/technology/red-hat-jboss-web-server-7-0-on-rhel-9.md) · [Red Hat JBoss Enterprise Application Platform 7](https://agentprime.io/advisories/technology/red-hat-jboss-enterprise-application-platform-7.md) · [Red Hat JBoss Enterprise Application Platform 8](https://agentprime.io/advisories/technology/red-hat-jboss-enterprise-application-platform-8.md) · [Red Hat JBoss Enterprise Application Platform Expansion Pack](https://agentprime.io/advisories/technology/red-hat-jboss-enterprise-application-platform-expansion-pack.md) · [Red Hat JBoss Web Server 5](https://agentprime.io/advisories/technology/red-hat-jboss-web-server-5.md) · [Red Hat JBoss Web Server 6](https://agentprime.io/advisories/technology/red-hat-jboss-web-server-6.md) · [Red Hat Single Sign-On 7](https://agentprime.io/advisories/technology/red-hat-single-sign-on-7.md) - **Published:** 19 Aug 2026 - **Updated:** 3 Nov 2026 - **Reviewed by a person:** No Published by the CVE Program (CNA: redhat) at 19 Aug 2026, 10:01 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. ## Affected products, as the CNA wrote them - Vendor: Red Hat. Product: Red Hat JBoss Web Server 7.0.3. - No versions given - Other versions: unaffected - Package name: `mod_cluster-core` - Collection: `https://access.redhat.com/downloads/content/package-browser/` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 7.0 on RHEL 10. - unaffected: `0:2.1.1-1.Final_redhat_00001.1.el10jws to before *` (rpm) - Other versions: affected - Package name: `jws7-mod_cluster` - Collection: `https://access.redhat.com/downloads/content/package-browser/` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 7.0 on RHEL 10. - unaffected: `0:11.0.21-10.redhat_00010.1.el10jws to before *` (rpm) - Other versions: affected - Package name: `jws7-tomcat` - Collection: `https://access.redhat.com/downloads/content/package-browser/` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 7.0 on RHEL 10. - unaffected: `0:1.3.7-4.redhat_4.el10jws to before *` (rpm) - Other versions: affected - Package name: `jws7-tomcat-native` - Collection: `https://access.redhat.com/downloads/content/package-browser/` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 7.0 on RHEL 8. - unaffected: `0:2.1.1-1.Final_redhat_00001.1.el8jws to before *` (rpm) - Other versions: affected - Package name: `jws7-mod_cluster` - Collection: `https://access.redhat.com/downloads/content/package-browser/` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 7.0 on RHEL 8. - unaffected: `0:11.0.21-10.redhat_00010.1.el8jws to before *` (rpm) - Other versions: affected - Package name: `jws7-tomcat` - Collection: `https://access.redhat.com/downloads/content/package-browser/` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 7.0 on RHEL 8. - unaffected: `0:1.3.7-4.redhat_4.el8jws to before *` (rpm) - Other versions: affected - Package name: `jws7-tomcat-native` - Collection: `https://access.redhat.com/downloads/content/package-browser/` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 7.0 on RHEL 9. - unaffected: `0:2.1.1-1.Final_redhat_00001.1.el9jws to before *` (rpm) - Other versions: affected - Package name: `jws7-mod_cluster` - Collection: `https://access.redhat.com/downloads/content/package-browser/` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 7.0 on RHEL 9. - unaffected: `0:11.0.21-10.redhat_00010.1.el9jws to before *` (rpm) - Other versions: affected - Package name: `jws7-tomcat` - Collection: `https://access.redhat.com/downloads/content/package-browser/` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 7.0 on RHEL 9. - unaffected: `0:1.3.7-4.redhat_4.el9jws to before *` (rpm) - Other versions: affected - Package name: `jws7-tomcat-native` - Collection: `https://access.redhat.com/downloads/content/package-browser/` - Vendor: Red Hat. Product: Red Hat JBoss Enterprise Application Platform 7. - No versions given - Other versions: affected - Package name: `mod_cluster-core` - Collection: `https://access.redhat.com/jbossnetwork/restricted/listSoftware.html` - Vendor: Red Hat. Product: Red Hat JBoss Enterprise Application Platform 8. - No versions given - Other versions: affected - Package name: `mod_cluster-core` - Collection: `https://access.redhat.com/jbossnetwork/restricted/listSoftware.html` - Vendor: Red Hat. Product: Red Hat JBoss Enterprise Application Platform Expansion Pack. - No versions given - Other versions: affected - Package name: `mod_cluster-core` - Collection: `https://access.redhat.com/jbossnetwork/restricted/listSoftware.html` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 5. - No versions given - Other versions: unknown - Package name: `mod_cluster-core` - Collection: `https://access.redhat.com/jbossnetwork/restricted/listSoftware.html` - Vendor: Red Hat. Product: Red Hat JBoss Web Server 6. - No versions given - Other versions: affected - Package name: `mod_cluster-core` - Collection: `https://access.redhat.com/jbossnetwork/restricted/listSoftware.html` - Vendor: Red Hat. Product: Red Hat Single Sign-On 7. - No versions given - Other versions: affected - Package name: `mod_cluster-core` - Collection: `https://access.redhat.com/downloads/content/package-browser/` ## Not analysed yet We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter. ## Severity and exploitation - 4.3 Medium, CVSS 3.1: `CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`, from CNA (redhat) - **CISA KEV:** Not listed. - **EPSS:** 0.027, the 86th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days. ## Timeline - 19 Aug 2026, 10:01 UTC: [Confirmed by the CVE List](https://www.cve.org/CVERecord?id=CVE-2026-76166) - 19 Aug 2026, 10:16 UTC: [Confirmed by NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-76166) ## Sources - [CVE List: CVE-2026-76166](https://www.cve.org/CVERecord?id=CVE-2026-76166) - [NVD: CVE-2026-76166](https://nvd.nist.gov/vuln/detail/CVE-2026-76166) ### References from the CNA - (vendor-advisory, redhat) - (vendor-advisory, redhat) - (vdb-entry, redhat) - (issue-tracking, redhat) Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description. ## Check whether this affects you This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. Compare the affected versions above with what you run. - With the agentprime MCP server (), `get_advisory` returns this record and `search_advisories` finds related ones. Setup: - As JSON: - Everything that needs attention now: --- The web page: . Everything for agents: .