CVE-2026-58208

CVE-2026-58208 affects NATS Server. A WebSocket listener could route requests for the MQTT-over-WebSocket path into MQTT handling even when MQTT was not configured, allowing an unauthenticated client with WebSocket access to reach an uninitialized MQTT state and crash the server process. This iss...

CVE-2026-58208 NATS Server: MQTT-over-WebSocket Path Can Crash WebSocket-Only JetStream Servers Before MQTT Is Enabled

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, a WebSocket listener could route requests for the MQTT-over-WebSocket path into MQTT handling even when MQTT was not configured, allowing an unauthenticated client with...

EUVD-2026-42391

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, a WebSocket listener could route requests for the MQTT-over-WebSocket path into MQTT handling even when MQTT was not configured, allowing an unauthenticated client with...

CVE-2026-58214

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, an authenticated MQTT client could subscribe to the internal $MQTT.deliver.pubrel subject family, bypassing configured subscribe permissions and exposing MQTT QoS2 protoc...

AZL-92256 CVE-2026-58209 affecting package telegraf for versions less than 1.31.0-27

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, MQTT retained message delivery and QoS1+ durable replay could deliver messages whose original topics matched a subscriber configured subscribe deny rule because these...

CVE-2026-58209

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, MQTT retained message delivery and QoS1+ durable replay could deliver messages whose original topics matched a subscriber configured subscribe deny rule because these...

EUVD-2026-42347

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, MQTT retained message delivery and QoS1+ durable replay could deliver messages whose original topics matched a subscriber configured subscribe deny rule because these...

CVE-2026-58209 NATS Server: MQTT retained and QoS replay bypass subscribe deny filters

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, MQTT retained message delivery and QoS1+ durable replay could deliver messages whose original topics matched a subscriber configured subscribe deny rule because these...

CVE-2026-58209 NATS Server: MQTT retained and QoS replay bypass subscribe deny filters

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, MQTT retained message delivery and QoS1+ durable replay could deliver messages whose original topics matched a subscriber configured subscribe deny rule because these...

CVE-2026-58209

NATS Server before versions 2.14.3 and 2.12.12 could deliver MQTT retained messages and QoS1+ durable replays to subscribers whose topics matched a deny rule, because delivery paths did not consistently re-check the original topic before sending MQTT PUBLISH. This issue is fixed in 2.14.3 and 2.1...

CVE-2026-58214 NATS Server: MQTT subscribe ACL bypass via $MQTT.deliver.pubrel prefix (incomplete fix for CVE-2026-33217)

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, an authenticated MQTT client could subscribe to the internal $MQTT.deliver.pubrel subject family, bypassing configured subscribe permissions and exposing MQTT QoS2 protoc...

CVE-2026-58214

CVE-2026-58214 – NATS Server (MQTT subscribe ACL bypass) Prior to version 2.14.3 and 2.12.12, an authenticated MQTT client could subscribe to the internal $MQTT.deliver.pubrel subject family, bypassing configured subscribe permissions and exposing MQTT QoS2 protocol metadata for sessions in the a...

CVE-2026-58214 NATS Server: MQTT subscribe ACL bypass via $MQTT.deliver.pubrel prefix (incomplete fix for CVE-2026-33217)

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, an authenticated MQTT client could subscribe to the internal $MQTT.deliver.pubrel subject family, bypassing configured subscribe permissions and exposing MQTT QoS2 protoc...

EUVD-2026-42383

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.1 and 2.12.9, an MQTT client could include protocol control characters in subscription filters that were later forwarded as NATS protocol data to route or leafnode connections, corrupti...

CVE-2026-58213

NATS Server (nats-server) before versions 2.14.1 and 2.12.9 is vulnerable: an MQTT client can include protocol control characters in subscription filters, which are later forwarded as NATS protocol data to route or leafnode connections. This corrupts the forwarded protocol stream and allows injec...

CVE-2026-58213 NATS Server: MQTT SUBSCRIBE Protocol Injection via Leaf Node/Route Forwarding allows arbitrary NATS command injection

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.1 and 2.12.9, an MQTT client could include protocol control characters in subscription filters that were later forwarded as NATS protocol data to route or leafnode connections, corrupti...

PT-2026-56560

Name of the Vulnerable Software and Affected Versions NATS Server versions prior to 2.14.3 NATS Server versions prior to 2.12.12 Description An unauthenticated MQTT client can cause the server to consume excessive memory by sending large incomplete MQTT CONNECT packets. The server retains these...

PT-2026-56561

Name of the Vulnerable Software and Affected Versions NATS Server versions prior to 2.14.1 NATS Server versions prior to 2.12.9 Description An MQTT client can include protocol control characters in subscription filters. These characters are subsequently forwarded as NATS protocol data to route or...

nats-server: NATS Server: Denial of Service via incomplete MQTT CONNECT packets

A flaw was found in NATS Server. An unauthenticated remote attacker could send large, incomplete MQTT CONNECT packets to the server. This action causes the server to retain these packets, consuming significant memory before authentication is complete. This can lead to a denial of service DoS...

nats-server: NATS Server: Protocol stream corruption and unintended operation injection via MQTT client subscription filters

A flaw was found in NATS Server. An authenticated MQTT client could exploit this by embedding protocol control characters within subscription filters. These characters would then be forwarded as NATS protocol data to route or leafnode connections, leading to the corruption of the protocol stream...