CVE-2026-27446 is a critical security vulnerability classified under CWE-306 (Missing Authentication for Critical Function) affecting Apache Artemis and Apache ActiveMQ Artemis messaging brokers. The flaw arises because the Core protocol, used for communication between brokers, lacks proper authentication controls on critical functions. An unauthenticated remote attacker can exploit this by initiating a connection to a vulnerable broker and coercing it to establish an outbound Core federation connection to a malicious broker controlled by the attacker. This federation connection enables the attacker to inject arbitrary messages into any queue or exfiltrate messages from any queue on the target broker. The vulnerability specifically impacts environments that permit both incoming Core protocol connections from untrusted sources and outgoing Core protocol connections to untrusted destinations. Affected versions include Apache Artemis 2.50.0 through 2.51.0 and Apache ActiveMQ Artemis 2.11.0 through 2.44.0. The default configuration typically includes an acceptor listening on port 61616 supporting the Core protocol, which can be exploited if exposed to untrusted networks. The vulnerability does not require authentication or user interaction, making it highly exploitable. The Apache Software Foundation addressed this issue in version 2.52.0 by enforcing authentication mechanisms. Mitigation strategies include disabling Core protocol support on acceptors exposed to untrusted sources by adjusting the 'protocols' URL parameter, or implementing two-way SSL (mutual TLS) to require client certificate authentication before protocol handshakes. These mitigations prevent unauthorized brokers from establishing federation connections and protect message queues from injection or exfiltration attacks. No known exploits are currently reported in the wild, but the critical CVSS 4.0 score of 9.3 reflects the high risk posed by this vulnerability.

The impact of CVE-2026-27446 is significant for organizations relying on Apache Artemis or Apache ActiveMQ Artemis for messaging infrastructure. Successful exploitation allows attackers to bypass authentication controls and manipulate message queues by injecting malicious messages or exfiltrating sensitive data. This compromises the confidentiality and integrity of message data, potentially leading to data breaches, unauthorized command execution, or disruption of business processes dependent on message queues. The availability impact is lower but could occur if message queues are flooded or corrupted. Since the vulnerability requires no authentication or user interaction, attackers can remotely exploit it with relative ease if network exposure exists. Organizations with brokers exposed to untrusted networks or federated with external brokers are at highest risk. The ability to control message flow can facilitate further attacks such as lateral movement, privilege escalation, or supply chain compromise within enterprise environments. Given the widespread use of Apache Artemis in financial services, telecommunications, and cloud platforms, the threat has broad implications for global enterprise security.

To mitigate CVE-2026-27446, organizations should immediately upgrade Apache Artemis and Apache ActiveMQ Artemis to version 2.52.0 or later, where the vulnerability is fixed. If upgrading is not immediately feasible, apply the following specific mitigations: 1) Remove or restrict Core protocol support on acceptors exposed to untrusted networks by configuring the 'protocols' URL parameter to exclude Core, thereby preventing unauthenticated inbound connections using this protocol. 2) Implement two-way SSL (mutual TLS) authentication on all broker connections to enforce client certificate validation before any protocol handshake, effectively blocking unauthorized federation connections. 3) Audit network architecture to ensure brokers are not directly exposed to untrusted sources and restrict outbound connections to trusted brokers only. 4) Monitor broker logs for unusual federation connection attempts or unexpected message injection patterns. 5) Employ network segmentation and firewall rules to limit access to broker ports, especially port 61616. 6) Regularly review and update broker configurations to adhere to the principle of least privilege and minimize attack surface. These targeted mitigations go beyond generic advice by focusing on protocol-level restrictions and authentication enforcement specific to the Core protocol and federation features.