CVE-2026-76166

What it is

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.

At a glance

Exploitability

Can be exploited from the same network segment without logging in. Limited direct impact.

Exploit odds

2.7% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2026-08-19 10:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-11-03 18:18 UTC Last updatedMost recent change to the record

Details

Published

2026-08-19 10:16 UTC

Last modified

2026-11-03 18:18 UTC

Exploit probability

2.7% · EPSS, next 30 days

Weakness

CWE-476 · NULL pointer dereference

Record status

Awaiting Analysis

Attack profile CVSS 3.1 · 4.3

Attack vector

Adjacent network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low