CVE-2026-76166
Modcluster-core: mod_cluster advertise listener: unauthenticated dos via crafted multicast datagram
- 4.3MediumCVSS base score
- 2.7%Exploitation in 30 daysEPSS · top 14% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By redhat
Published
- 3 months later
· 3 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| redhatCNA (assigner) | 3.1 | Medium4.3 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
| NVDNVD · Awaiting Analysis | 3.1 | Medium4.3 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
- EPSS (exploitation in 30 days)
- 2.7% · top 14% of all CVEs (9 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.3.
Affected products
Red Hat · Red Hat JBoss Web Server 6.2.6
All versions: unaffected
Red Hat · Red Hat JBoss Web Server 6.2 on RHEL 10
- unaffected 0:2.0.5-1.Final_redhat_00001.1.el10jws – < *
Red Hat · Red Hat JBoss Web Server 6.2 on RHEL 10
- unaffected 0:10.1.49-18.redhat_00018.1.el10jws – < *
Red Hat · Red Hat JBoss Web Server 6.2 on RHEL 10
- unaffected 0:1.3.6-2.redhat_2.el10jws – < *
Red Hat · Red Hat JBoss Web Server 6.2 on RHEL 8
- unaffected 0:2.0.5-1.Final_redhat_00001.1.el8jws – < *
Red Hat · Red Hat JBoss Web Server 6.2 on RHEL 8
- unaffected 0:10.1.49-18.redhat_00018.1.el8jws – < *
Red Hat · Red Hat JBoss Web Server 6.2 on RHEL 8
- unaffected 0:1.3.6-2.redhat_2.el8jws – < *
Red Hat · Red Hat JBoss Web Server 6.2 on RHEL 9
- unaffected 0:2.0.5-1.Final_redhat_00001.1.el9jws – < *
Red Hat · Red Hat JBoss Web Server 6.2 on RHEL 9
- unaffected 0:10.1.49-18.redhat_00018.1.el9jws – < *
Red Hat · Red Hat JBoss Web Server 6.2 on RHEL 9
- unaffected 0:1.3.6-2.redhat_2.el9jws – < *
Red Hat · Red Hat JBoss Web Server 7.0.3
All versions: unaffected
Red Hat · Red Hat JBoss Web Server 7.0 on RHEL 10
- unaffected 0:2.1.1-1.Final_redhat_00001.1.el10jws – < *
Red Hat · Red Hat JBoss Web Server 7.0 on RHEL 10
- unaffected 0:11.0.21-10.redhat_00010.1.el10jws – < *
Red Hat · Red Hat JBoss Web Server 7.0 on RHEL 10
- unaffected 0:1.3.7-4.redhat_4.el10jws – < *
Red Hat · Red Hat JBoss Web Server 7.0 on RHEL 8
- unaffected 0:2.1.1-1.Final_redhat_00001.1.el8jws – < *
Red Hat · Red Hat JBoss Web Server 7.0 on RHEL 8
- unaffected 0:11.0.21-10.redhat_00010.1.el8jws – < *
Red Hat · Red Hat JBoss Web Server 7.0 on RHEL 8
- unaffected 0:1.3.7-4.redhat_4.el8jws – < *
Red Hat · Red Hat JBoss Web Server 7.0 on RHEL 9
- unaffected 0:2.1.1-1.Final_redhat_00001.1.el9jws – < *
Red Hat · Red Hat JBoss Web Server 7.0 on RHEL 9
- unaffected 0:11.0.21-10.redhat_00010.1.el9jws – < *
Red Hat · Red Hat JBoss Web Server 7.0 on RHEL 9
- unaffected 0:1.3.7-4.redhat_4.el9jws – < *
Red Hat · Red Hat JBoss Enterprise Application Platform 7
All versions: affected
Red Hat · Red Hat JBoss Enterprise Application Platform 8
All versions: affected
Red Hat · Red Hat JBoss Enterprise Application Platform Expansion Pack
All versions: affected
Red Hat · Red Hat JBoss Web Server 5
All versions: unknown
Red Hat · Red Hat Single Sign-On 7
All versions: affected
What to do
Workaround: Disable multicast-based proxy advertisement and use static proxy configuration instead. When advertisement must be enabled, ensure the multicast network segment (default 224.0.1.105:23364) is properly isolated and not accessible from untrusted network segments.
References
6
- RHSA-2026:93618 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:93622 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:96228 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:96229 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-76166 (opens in a new tab)vdb-entryx_refsource_REDHAT
- RHBZ#2510883 (opens in a new tab)issue-trackingx_refsource_REDHAT
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-62367 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-76166)Record last updated .