CVE-2026-49363
Description
A missing authentication vulnerability was found in Apache ActiveMQ Artemis. The SUBSCRIBE_TOPOLOGY_V2 handler in CoreProtocolManager.LocalChannelHandler.handlePacket() processes topology subscription requests on channel0 with zero authentication -- no call to getSecurityStore(), no credential verification, no subject validation. An unauthenticated attacker can send a single 5-byte packet on the CORE protocol (via :8080 HTTP-upgrade in EAP or :61616 in AMQ Broker) to obtain the broker's nodeID (type-1 UUID embedding MAC address), internal hostname/IP, port numbers, connector configurations, and backup/scale-down group names. In clustered deployments, a persistent ClusterTopologyListener is registered that continuously pushes all topology changes to the unauthenticated client. This contrasts with the federation handler in the same file which was fixed via ARTEMIS-5928 (CVE-2026-27446). The leaked nodeID UUID seed directly enables session-name brute-force for REATTACH_SESSION session hijack.
Mitigation
1. Remove Core protocol from internet-facing acceptors -- configure the protocols parameter to exclude Core protocol on any acceptor receiving untrusted connections. In EAP, the :8080 HTTP-upgrade acceptor supports Core by default; restricting to AMQP/STOMP/OpenWire prevents the attack entirely.
2. Enable mutual TLS -- configure sslEnabled=true with needClientAuth=true on all Core protocol acceptors. TLS handshake failure occurs before any protocol-level packet can be sent.
3. Disable HTTP-upgrade for Core protocol if not required -- remove the http-upgrade element from the Artemis acceptor configuration to eliminate the :8080 attack surface.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | Low | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | None | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Understanding the Weakness (CWE)
Access Control,Other
Technical Impact: Gain Privileges or Assume Identity; Varies by Context
Exposing critical functionality essentially provides an attacker with the privilege level of that functionality. The consequences will depend on the associated functionality, but they can range from reading or modifying sensitive data, accessing administrative or other privileged functionality, or possibly even executing arbitrary code.
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