Is there a public exploit for CVE-2026-76166?

No public exploit for CVE-2026-76166 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-76166?

CVE-2026-76166 scores CVSS 4.3 (v3.1), rated medium. EPSS puts the chance of exploitation in the next 30 days at 1.03%.

What does CVE-2026-76166 affect?

CVE-2026-76166 affects Red Hat Red Hat JBoss Web Server 7.0 on RHEL 9, Red Hat JBoss Web Server 7.0 on RHEL 8, Red Hat JBoss Web Server 7.0 on RHEL 10.

4.3 Medium

A flaw was found in modcluster's AdvertiseListenerImpl (org.jboss.modcluster core module).

CVE-2026-76166

A flaw was found in modcluster'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.

Assessment

CVSS: 4.3 (v3.1)
Severity: Medium
EPSS: 1.03% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 19 August 2026
Last updated: 3 November 2026
Affected: Red Hat · 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
Assigner: redhat

CVSS vectorCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

At the source

EUVD (ENISA)

References

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