CVE-2026-57967: Unauthenticated Remote Session Hijacking via CORE Protocol Reattachment in Apache ActiveMQ Artemis
HERMES THREAT SCORE & BROKER SESSION HIJACKING
Target:Apache ActiveMQ Artemis — CORE Protocol Engine (TCP Port 61616) & ServerSessionImpl CVSS v3.1 rates CVE-2026-57967 at 9.8 (CRITICAL) with maximum impact scores across Confidentiality, Integrity, and Availability. Hermes corroborates extreme systemic criticality at HTS 96. ActiveMQ Artemis serves as the asynchronous message broker backbone for core banking transactional networks, telecom routing, distributed microservices, and industrial SCADA backplanes. Because the CORE protocol (default TCP port 61616) accepted unauthenticated session reattach packets without validating proof-of-possession tokens, any unauthenticated network attacker can usurp active administrative and producer sessions, drain confidential message queues, inject forged transactions, and cause catastrophic operational disruption.
HASS AGENTIC SEVERITY & EVENT-DRIVEN BUS POISONING
Target:Enterprise Event Bus, Agentic Task Queues & Asynchronous Tool Execution Workers In modern agentic architectures, distributed LLM agents and background orchestrators utilize asynchronous message queues (JMS, AMQP, and CORE) to dispatch tool invocations, persist memory states, and exchange task directives. Hijacking an established session allows an adversary to intercept inter-agent commands, inject spoofed prompts into worker queues, and manipulate decision pipelines across the enterprise.
CVE-2026-57967: Unauthenticated Remote Session Hijacking via CORE Protocol Reattachment in Apache ActiveMQ ArtemisVULNERABILITY
Software platform affected by security vulnerabilities and agentic attack patterns.
🔍 Why is this related? (Evidence & Provenance)
“Confirmed security vulnerability in Microsoft Office & 365 Apps documented in Hermes dossier.”
- [vulnerability_report]
- [government_confirmation]CISA verified active exploitation in the wild and mandated federal remediation deadline in KEV entry. — Source: Cybersecurity & Infrastructure Security Agency (CISA): CISA Adds CVE-2026-59822 to Known Exploited Vulnerabilities Catalog (Reliability: VERY_HIGH)
1. Technical Context & Affected Software Matrix
Section titled “1. Technical Context & Affected Software Matrix”ActiveMQ Artemis exposes the native CORE protocol (commonly over TCP port 61616) alongside open standards such as AMQP, MQTT, STOMP, and OpenWire. The vulnerability specifically targets the CORE protocol connection handler.
| Parameter | Technical Specification | Operational Significance |
|---|---|---|
| CVE Identifier | CVE-2026-57967 | Official Apache Advisory Reference |
| Vulnerability Class | Authentication Bypass (CWE-287) | Missing authentication on session reattachment |
| Vulnerable Component | artemis-server — CORE Protocol Handler | Packet parser handling PacketImpl.SESS_REATTACH |
| Trigger Mechanism | Crafted SessionReattachMessage packet | Reassociates TCP transport channel to existing ServerSessionImpl |
| Default Port / Transport | TCP 61616 (CORE protocol) | Exposed across internal enterprise subnets and broker meshes |
| Privileges Required | None (PR:N) | Attacker needs only reachability to the broker’s listening port |
| User Interaction | None (UI:N) | Entirely remote, automated attack |
| Affected Versions | org.apache.artemis:artemis-server 2.50.0 - 2.56.0org.apache.activemq:artemis-server 1.0.0 - 2.44.0 | Production enterprise messaging hubs and cloud brokers |
| Remediated Version | 2.57.0 | Requires session secret verification token during reattachment |
2. Vulnerability Anatomy & Root Cause Analysis
Section titled “2. Vulnerability Anatomy & Root Cause Analysis”The CORE Protocol Session Lifecycle
Section titled “The CORE Protocol Session Lifecycle”In ActiveMQ Artemis, when a client connects over the CORE protocol:
- It sends a
CreateSessionMessagecarrying credentials (username and password or mutual TLS certificate). - The broker verifies the credentials against JAAS or security plugins and allocates an internal session object (
ServerSessionImpl) with a uniquenameor session ID. - The session is registered in the broker’s central session table (
SessionManager). - To handle transient network instability without requiring full credential renegotiation, the CORE protocol includes a reconnect feature: a client disconnects, reconnects on a new TCP socket, and sends a
SessionReattachMessagecontaining the original session ID.
The Missing Authentication Flaw
Section titled “The Missing Authentication Flaw”In affected versions of Artemis, the handler for PacketImpl.SESS_REATTACH executed the following flawed logic:
// Flawed logic in affected ServerSessionPacketHandlerPacket packet = decode(buffer);if (packet.getType() == PacketImpl.SESS_REATTACH) { SessionReattachMessage reattach = (SessionReattachMessage) packet; String sessionName = reattach.getName();
// Look up existing session solely by name/identifier ServerSessionImpl existingSession = sessionManager.getSession(sessionName);
if (existingSession != null) { // DETACH original transport connection existingSession.getRemotingConnection().disconnect();
// ATTACH new transport channel without verifying credentials or tokens! existingSession.transferConnection(newRemotingConnection);
sendConfirmation(newRemotingConnection); return; // Session successfully hijacked! }}Notice the critical absence of verification:
- The broker does not demand the client’s password or an ephemeral cryptographic reattachment token.
- It does not verify that the new connection originates from the same remote IP address or TLS identity.
- It immediately severs the legitimate client’s active transport socket, effectively performing a Denial of Service against the legitimate subscriber/producer while granting the adversary full operational rights.
3. Threat Vectors, Exploitation Mechanics & Attack Flow
Section titled “3. Threat Vectors, Exploitation Mechanics & Attack Flow”Attack Flow Architecture
Section titled “Attack Flow Architecture”flowchart TD A["Legitimate Client / Microservice"] -->|"1. Authenticates with credentials"| B["ActiveMQ Artemis Broker (TCP 61616)"] B -->|"2. Establishes ServerSessionImpl (Session-ID: SESS-7812)"| B C["Unauthenticated Adversary"] -->|"3. Connects to TCP 61616"| B C -->|"4. Sends SESS_REATTACH packet (name='SESS-7812')"| B B -->|"5. Forcibly disconnects legitimate client transport"| A B -->|"6. Rebinds SESS-7812 to attacker TCP socket"| C C -->|"7. Consumes confidential messages / Injects forged orders"| B C -->|"8. Dispatches broker management commands"| D["Enterprise Database / Agent Runtimes"]Exploit Execution Flow
Section titled “Exploit Execution Flow”-
Reconnaissance / Session Enumeration: An attacker on the internal network connects to TCP port 61616. Session IDs in Artemis follow predictable formats or can be brute-forced / observed via unencrypted internal communications or network-adjacent packet captures.
-
Packet Transmission: The attacker transmits a raw binary packet structured as an Artemis CORE
SESS_REATTACH:- Packet Type:
0x1A(SESS_REATTACH) - Target Session Name:
client-orders-queue-9981 - Last Confirmed Command Sequence:
0
- Packet Type:
-
Session Seizure: The broker closes the TCP stream of the legitimate client application. The legitimate application enters a reconnect loop. Meanwhile, the attacker’s socket receives a confirmation response (
SESS_REATTACH_RESP). -
Payload Extraction & Injection: The attacker issues
SESS_CONSUMER_CREATEandSESS_SENDcommands to:- Drain sensitive messages awaiting processing (PII, credentials, payment records).
- Inject fraudulent messages directly into downstream processing queues.
- Delete destination queues or alter broker configuration if the hijacked session possessed administrative permissions.
4. Doctrinal Impact on Enterprise Infrastructure & Multi-Agent Meshes
Section titled “4. Doctrinal Impact on Enterprise Infrastructure & Multi-Agent Meshes”1. Enterprise Financial & Supply-Chain Backbone Compromise
Section titled “1. Enterprise Financial & Supply-Chain Backbone Compromise”In financial institutions, retail payment processors, and healthcare environments, ActiveMQ Artemis transmits transactional records. The ability to intercept and modify messages in transit breaks ACID guarantees, leading to fraudulent fund transfers or altered medical commands.
2. Multi-Agent System Control Inversion
Section titled “2. Multi-Agent System Control Inversion”Distributed agentic workflows use message brokers to decouple reasoning engines from executor tools. An adversary hijacking an agent’s consumer session can intercept task prompts, tamper with tool outputs, or inject malicious instructions into downstream worker queues, subverting the entire agent collective.
3. Broker Denial of Service & Cascading Outages
Section titled “3. Broker Denial of Service & Cascading Outages”By continually firing SESSION_REATTACH packets across detected session IDs, an attacker can trigger perpetual disconnection loops, grinding enterprise microservices to an immediate standstill.
5. Threat Hunting, Detection & Forensic Investigation
Section titled “5. Threat Hunting, Detection & Forensic Investigation”Zeek / Bro Network Detection Script
Section titled “Zeek / Bro Network Detection Script”Monitor the Artemis CORE protocol port for unexpected session reattachments:
event artemis_core_message(c: connection, is_orig: bool, packet_type: count, session_name: string) { if (packet_type == 26 && c$id$resp_p == 61616/tcp) { # Check if the IP reattaching does not match previous authenticated sessions NOTICE([$note=Notice::Action, $msg=fmt("Suspicious unauthenticated Artemis CORE session reattach from %s for session %s", c$id$orig_h, session_name), $conn=c, $identifier=cat(c$id$orig_h, session_name)]); }}Sigma Rule: Suspicious High-Frequency Disconnections and Reattachments
Section titled “Sigma Rule: Suspicious High-Frequency Disconnections and Reattachments”title: Apache ActiveMQ Artemis CORE Protocol Session Takeover (CVE-2026-57967)id: cve-2026-57967-artemis-session-hijackstatus: experimentaldescription: Detects rapid client disconnection events followed immediately by session reattachment from anomalous source IP addresses in Apache ActiveMQ Artemis logs.author: Hermes Codex Threat Intelligencedate: 2026-09-14references: - https://lists.apache.org/thread/fxfjqrdsnksw5f17zs3yqo864lblgv6y - https://nvd.nist.gov/vuln/detail/CVE-2026-57967tags: - attack.lateral_movement - attack.t1557 - attack.t1078logsource: product: activemq_artemis service: brokerdetection: selection_log: message|contains: - "AMQ222033" # Session was disconnected - "AMQ222034" # Session reattached condition: selection_logfalsepositives: - Transient network flapping causing legitimate clients to re-establish sessions within expected cluster subnets.level: high6. MITRE ATT&CK Mapping
Section titled “6. MITRE ATT&CK Mapping”| Tactical Phase | Technique ID | Technique Name | Exploitation Context |
|---|---|---|---|
| Initial Access | T1190 | Exploit Public-Facing Application | Connecting to unprotected broker port 61616 |
| Lateral Movement | T1557 | Adversary-in-the-Middle | Session reattachment hijacking ongoing communications |
| Privilege Escalation | T1078 | Valid Accounts | Inheriting the authenticated session’s pre-existing privileges |
| Defense Evasion | T1562.001 | Disable or Modify Tools | Evicting legitimate monitoring and telemetry consumers |
| Collection | T1005 | Data from Local System | Draining messages and sensitive payloads from broker queues |
| Impact | T1499.004 | Endpoint Denial of Service: Application Exhaustion | Forcibly disconnecting legitimate enterprise workers |
7. Comprehensive Remediation & Hardening Guide
Section titled “7. Comprehensive Remediation & Hardening Guide”1. Upgrade to Apache ActiveMQ Artemis 2.57.0 Immediately
Section titled “1. Upgrade to Apache ActiveMQ Artemis 2.57.0 Immediately”Deploy the official patch release 2.57.0, which mandates that any SESSION_REATTACH packet provide a cryptographically secure session confirmation token that matches the original session’s authorization context:
# Verify broker version./bin/artemis version
# Upgrade standalone broker instance./bin/artemis-service stop# Replace lib/ jars with version 2.57.0 artifacts./bin/artemis-service start2. Network-Level Segmentation & Firewalls
Section titled “2. Network-Level Segmentation & Firewalls”Broker listeners on port 61616 must never be exposed to public networks or untrusted client segments. Enforce strict firewall rules allowing only known application servers and worker pools:
# Restrict access to TCP 61616 using iptables / nftablesiptables -A INPUT -p tcp --dport 61616 -s 10.200.0.0/16 -j ACCEPTiptables -A INPUT -p tcp --dport 61616 -j DROP3. Enforce Mutual TLS (mTLS) Authentication
Section titled “3. Enforce Mutual TLS (mTLS) Authentication”Configure TLS with client certificate authentication (needClientAuth=true) on the CORE acceptor in broker.xml. This prevents unauthorized TCP sockets from connecting to port 61616 even if network reachability exists:
<acceptor name="artemis"> tcp://0.0.0.0:61616?tcpSendBufferSize=1048576;sslEnabled=true;keyStorePath=/etc/artemis/keystore.jks;keyStorePassword=ENC(...);trustStorePath=/etc/artemis/truststore.jks;trustStorePassword=ENC(...);needClientAuth=true</acceptor>