Modcluster-core: mod_cluster advertise listener: unauthenticated dos via crafted multicast datagram
Priority LOW 25CWE-476Published · Updated
Key facts
- Attack vector
- Adjacent network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Partial Red Hat: 4 fixed, 6 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-476.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.02718 86th percentileScored 2026-11-07
Fix Partial Red Hat: 2 advisoriesRed Hat: 4 fixed, 6 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Red Hat | Red Hat JBoss Web Server 7.0.3 | — | — | Not affected | CNA |
| Red Hat | Red Hat JBoss Web Server 7.0 on RHEL 10 | — | 2.1.1-1.Final_redhat_00001.1.el10jws | Patch available | CNA |
| Red Hat | Red Hat JBoss Web Server 7.0 on RHEL 10 | — | 11.0.21-10.redhat_00010.1.el10jws | Patch available | CNA |
| Red Hat | Red Hat JBoss Web Server 7.0 on RHEL 10 | — | 1.3.7-4.redhat_4.el10jws | Patch available | CNA |
| Red Hat | Red Hat JBoss Web Server 7.0 on RHEL 8 | — | 2.1.1-1.Final_redhat_00001.1.el8jws | Patch available | CNA |
| Red Hat | Red Hat JBoss Web Server 7.0 on RHEL 8 | — | 11.0.21-10.redhat_00010.1.el8jws | Patch available | CNA |
| Red Hat | Red Hat JBoss Web Server 7.0 on RHEL 8 | — | 1.3.7-4.redhat_4.el8jws | Patch available | CNA |
| Red Hat | Red Hat JBoss Web Server 7.0 on RHEL 9 | — | 2.1.1-1.Final_redhat_00001.1.el9jws | Patch available | CNA |
| Red Hat | Red Hat JBoss Web Server 7.0 on RHEL 9 | — | 11.0.21-10.redhat_00010.1.el9jws | Patch available | CNA |
| Red Hat | Red Hat JBoss Web Server 7.0 on RHEL 9 | — | 1.3.7-4.redhat_4.el9jws | Patch available | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform Expansion Pack | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Web Server 5 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Web Server 6 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Single Sign-On 7 | — | — | No fix listed | CNA |
- Red Hat JBoss Web Server 7.0.3 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat JBoss Web Server 7.0 on RHEL 10 VendorRed Hat Affected — Fixed in 2.1.1-1.Final_redhat_00001.1.el10jws Patch available CNA
- Red Hat JBoss Web Server 7.0 on RHEL 10 VendorRed Hat Affected — Fixed in 11.0.21-10.redhat_00010.1.el10jws Patch available CNA
- Red Hat JBoss Web Server 7.0 on RHEL 10 VendorRed Hat Affected — Fixed in 1.3.7-4.redhat_4.el10jws Patch available CNA
- Red Hat JBoss Web Server 7.0 on RHEL 8 VendorRed Hat Affected — Fixed in 2.1.1-1.Final_redhat_00001.1.el8jws Patch available CNA
- Red Hat JBoss Web Server 7.0 on RHEL 8 VendorRed Hat Affected — Fixed in 11.0.21-10.redhat_00010.1.el8jws Patch available CNA
- Red Hat JBoss Web Server 7.0 on RHEL 8 VendorRed Hat Affected — Fixed in 1.3.7-4.redhat_4.el8jws Patch available CNA
- Red Hat JBoss Web Server 7.0 on RHEL 9 VendorRed Hat Affected — Fixed in 2.1.1-1.Final_redhat_00001.1.el9jws Patch available CNA
- Red Hat JBoss Web Server 7.0 on RHEL 9 VendorRed Hat Affected — Fixed in 11.0.21-10.redhat_00010.1.el9jws Patch available CNA
- Red Hat JBoss Web Server 7.0 on RHEL 9 VendorRed Hat Affected — Fixed in 1.3.7-4.redhat_4.el9jws Patch available CNA
- Red Hat JBoss Enterprise Application Platform 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 8 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform Expansion Pack VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Web Server 5 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Web Server 6 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Single Sign-On 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
CPE names CNA · 10
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:/a:redhat:jboss_enterprise_web_server:7.0 | 7.0 | — | Red Hat |
| cpe:/a:redhat:jboss_enterprise_web_server:7.0::el10 | 7.0 | — | Red Hat |
| cpe:/a:redhat:jboss_enterprise_web_server:7.0::el8 | 7.0 | — | Red Hat |
| cpe:/a:redhat:jboss_enterprise_web_server:7.0::el9 | 7.0 | — | Red Hat |
| cpe:/a:redhat:jboss_enterprise_application_platform:7 | 7 | — | Red Hat |
| cpe:/a:redhat:jboss_enterprise_application_platform:8 | 8 | — | Red Hat |
| cpe:/a:redhat:jbosseapxp | — | — | Red Hat |
| cpe:/a:redhat:jboss_enterprise_web_server:5 | 5 | — | Red Hat |
| cpe:/a:redhat:jboss_enterprise_web_server:6 | 6 | — | Red Hat |
| cpe:/a:redhat:red_hat_single_sign_on:7 | 7 | — | Red Hat |
- cpe:/a:redhat:jboss_enterprise_web_server:7.0 Versions 7.0 — ·Red Hat
- cpe:/a:redhat:jboss_enterprise_web_server:7.0::el10 Versions 7.0 — ·Red Hat
- cpe:/a:redhat:jboss_enterprise_web_server:7.0::el8 Versions 7.0 — ·Red Hat
- cpe:/a:redhat:jboss_enterprise_web_server:7.0::el9 Versions 7.0 — ·Red Hat
- cpe:/a:redhat:jboss_enterprise_application_platform:7 Versions 7 — ·Red Hat
- cpe:/a:redhat:jboss_enterprise_application_platform:8 Versions 8 — ·Red Hat
- cpe:/a:redhat:jbosseapxp Versions — — ·Red Hat
- cpe:/a:redhat:jboss_enterprise_web_server:5 Versions 5 — ·Red Hat
- cpe:/a:redhat:jboss_enterprise_web_server:6 Versions 6 — ·Red Hat
- cpe:/a:redhat:red_hat_single_sign_on:7 Versions 7 — ·Red Hat
Remediation
Red Hat 2 advisories
- RHSA-2026:93618 Released 2026-11-03 · Red Hat rating ImportantRed Hat JBoss Web Server 7.0.3 release and security update
- Red Hat JBoss Web Server 7.0 on RHEL 10 jws7-mod_cluster-2.1.1-1.Final_redhat_00001.1.el10jws, jws7-mod_cluster-tomcat-2.1.1-1.Final_redhat_00001.1.el10jws, jws7-tomcat-11.0.21-10.redhat_00010.1.el10jws +10
- Red Hat JBoss Web Server 7.0 on RHEL 8 jws7-mod_cluster-2.1.1-1.Final_redhat_00001.1.el8jws, jws7-mod_cluster-tomcat-2.1.1-1.Final_redhat_00001.1.el8jws, jws7-tomcat-11.0.21-10.redhat_00010.1.el8jws +10
- Red Hat JBoss Web Server 7.0 on RHEL 9 jws7-mod_cluster-2.1.1-1.Final_redhat_00001.1.el9jws, jws7-mod_cluster-tomcat-2.1.1-1.Final_redhat_00001.1.el9jws, jws7-tomcat-11.0.21-10.redhat_00010.1.el9jws +10
- RHSA-2026:93622 Released 2026-11-03 · Red Hat rating ImportantRed Hat JBoss Web Server 7.0.3 release and security update
- Red Hat JBoss Web Server 7.0.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat JBoss Enterprise Application Platform 7 | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Enterprise Application Platform 8 | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Enterprise Application Platform Expansion Pack | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Web Server 5 | Affected | No fix planned: Out of support scope |
| Red Hat JBoss Web Server 6 | Affected | No fix yet |
| Red Hat Single Sign-On 7 | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Web Server 7.0 on RHEL 10 | Fixed | RHSA-2026:93618 |
| Red Hat JBoss Web Server 7.0 on RHEL 8 | Fixed | RHSA-2026:93618 |
| Red Hat JBoss Web Server 7.0 on RHEL 9 | Fixed | RHSA-2026:93618 |
| Red Hat JBoss Web Server 7.0.3 | Fixed | RHSA-2026:93622 |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-76166
- 2026-10-03 Alias added: GHSA-p4rg-ffff-6pmm
- 2026-11-03 Fix available: jws7-mod_cluster@0:2.1.1-1.Final_redhat_00001.1.el10jws, jws7-mod_cluster@0:2.1.1-1.Final_redhat_00001.1.el8jws, jws7-mod_cluster@0:2.1.1-1.Final_redhat_00001.1.el9jws +6 · CNA
- 2026-11-03 2 new references · CNA
- 2026-11-03 Fix available: RHSA-2026:93622 · Red Hat
- 2026-11-03 Fix available: RHSA-2026:93618 · Red Hat
- 2026-11-03 Fix available: Red Hat JBoss Web Server 7.0 on RHEL 10, Red Hat JBoss Web Server 7.0 on RHEL 8, Red Hat JBoss Web Server 7.0 on RHEL 9 +1 · Red Hat
References
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- TI-2018-16080 A code execution vulnerability exists in the Stapler web framework used by Jenkins 2.153… KEVCVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-76166 · CVE Program
- CVE-2026-76166 · NVD
- FIRST EPSS
- GHSA-p4rg-ffff-6pmm · GitHub Advisory Database · CC BY 4.0
- CVE-2026-76166 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences