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CVE-2026-76166— Modcluster-core: mod_cluster advertise listener: unauthenticated dos via crafted multicast datagram

Quick assessment

Affected
Red Hat Red Hat JBoss Enterprise Application Platform 7
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Modcluster mod_cluster是Modcluster社区的一个负载均衡软件。 mod_cluster存在异常处理不当漏洞，该漏洞源于AdvertiseListenerImpl组件未正确处理特制的UDP组播数据报，导致verifyDigest()函数发生空指针解引用，使advertise listener线程永久终止，造成拒绝服务。

CVSS 4.3 · Medium EPSS 1.03% · P63
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I. Basic Information for CVE-2026-76166

Vulnerability Information
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Vulnerability Title
Modcluster-core: mod_cluster advertise listener: unauthenticated dos via crafted multicast datagram
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
空指针解引用
Source: CVE Program / CVE List V5
Vulnerability Title
mod_cluster 异常处理不当漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Modcluster mod_cluster是Modcluster社区的一个负载均衡软件。 mod_cluster存在异常处理不当漏洞，该漏洞源于AdvertiseListenerImpl组件未正确处理特制的UDP组播数据报，导致verifyDigest()函数发生空指针解引用，使advertise listener线程永久终止，造成拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Red Hat Red Hat JBoss Enterprise Application Platform 7 - cpe:/a:redhat:jboss_enterprise_application_platform:7
Red Hat Red Hat JBoss Enterprise Application Platform 8 - cpe:/a:redhat:jboss_enterprise_application_platform:8
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack - cpe:/a:redhat:jbosseapxp
Red Hat Red Hat JBoss Web Server 5 - cpe:/a:redhat:jboss_enterprise_web_server:5
Red Hat Red Hat JBoss Web Server 6 - cpe:/a:redhat:jboss_enterprise_web_server:6
Red Hat Red Hat JBoss Web Server 7 - cpe:/a:redhat:jboss_enterprise_web_server:7
Red Hat Red Hat Single Sign-On 7 - cpe:/a:redhat:red_hat_single_sign_on:7

II. Public POCs for CVE-2026-76166

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III. Intelligence Information for CVE-2026-76166

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Vendor Advisories for CVE-2026-76166 (2)

Same Patch Batch · Red Hat · 2026-08-19 · 10 CVEs total

CVE-2026-70496 9.9 CRITICAL Search-v2-operator: search-v2-operator: operator clusterrole is cluster-admin equivalent v
CVE-2026-66794 9.3 CRITICAL Cluster-proxy-addon: cluster-proxy-addon: unauthenticated ssrf to arbitrary managed-cluste
CVE-2026-71470 9.1 CRITICAL Acm-search-v2-rhel9: search-v2-operator: search cr imageoverride/arguments/envvar flow uns
CVE-2026-76139 8.0 HIGH Acm-operator-bundle: acm-operator-bundle: bundle build execs unpinned stolostron/release@m
CVE-2026-75569 7.7 HIGH Mce-operator-bundle: all github actions pinned by mutable tag, not commit sha
CVE-2026-76235 7.5 HIGH Cockpit-ws: cockpit: cockpit-ws: unauthenticated remote memory leak via cockpitlang cookie
CVE-2026-76827 6.8 MEDIUM Search-indexer: search-indexer: update/delete operations not scoped to caller's cluster (c
CVE-2026-18874 6.2 MEDIUM Volsync-addon-controller: volsync-addon-controller: annotation values rendered into yaml v
CVE-2026-75900 6.1 MEDIUM Swtpm: swtpm: out-of-bounds read in swtpm_nvram_checkheader due to sizeof(pointer) vs size

IV. Related Vulnerabilities

Same product: Red Hat JBoss Enterprise Application Platform 7
Same vendor: Red Hat
Same weakness: CWE-476

V. Comments for CVE-2026-76166

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