PT-2026-56559

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 MQTT retained message delivery and QoS1+ durable replay may deliver messages to subscribers even if the original topics match a configured subscribe deny...

CVE-2026-58209: Incorrect Authorization

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-2026-58214: Incorrect Authorization

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-2026-58254: Incorrect Authorization

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.8, message trace destination checks were applied to ordinary client connections but not consistently to messages arriving through leafnode connections, allowing a leafnode...

PT-2026-56537

Name of the Vulnerable Software and Affected Versions NATS Server versions prior to 2.14.0 NATS Server versions prior to 2.12.7 NATS Server versions prior to 2.11.16 Description An authenticated user with subscription deny permissions can bypass a plain subject deny rule by utilizing a queue...

PT-2026-56581

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 A client capable of sending account-scoped connection monitoring requests can cause the server to crash. This occurs when the client provides Offset and Lim...

CVE-2026-58208: Uncaught Exception

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-2026-58211: Incorrect Authorization

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 client could be registered as the configured noauthuser through a parser path used when the first client operation was not CONNECT, bypassing user-level connection...

CVE-2026-58210: Uncontrolled Resource Consumption

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 unauthenticated MQTT client could cause the server to retain large incomplete MQTT CONNECT packets before authentication completed, consuming server memory while the...

CVE-2026-58250: NULL Pointer Dereference

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.12.8 and 2.11.17, an unauthenticated peer with network access to a leafnode listener with compression enabled could crash the server during the pre-authentication leafnode handshake by...

CVE-2026-58252: Improper Authorization

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, an authenticated user could receive messages on denied subjects when a wildcard subscription overlapped with a configured wildcard deny rule but was not a subset...

CVE-2026-58207: Integer Overflow or Wraparound

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 client able to send account-scoped connection monitoring requests could crash the server by supplying Connz pagination Offset and Limit values that overflowed internal...

PT-2026-56562

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 authenticated MQTT client can subscribe to the internal $MQTT.deliver.pubrel subject family. This action allows the client to bypass configured subscribe...

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...

CVE-2026-58213: Improper Neutralization of Special Elements in Output Used by a Downstream Component

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-2026-58253: Improper Authentication

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, when noauthuser was configured, a parser fast path intended for ordinary client connections could also apply to route or leafnode listeners, allowing an...

CVE-2026-58251: Improper Authorization

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, an authenticated user with subscription deny permissions could bypass a plain subject deny rule by using a queue subscription, because queue-specific deny...

PT-2026-56583

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 A flaw exists where a client can be registered as the configured no auth user via a parser path triggered when the initial client operation is not CONNECT...

PT-2026-56565

Name of the Vulnerable Software and Affected Versions NATS Server versions prior to 2.14.0 NATS Server versions prior to 2.12.7 NATS Server versions prior to 2.11.16 Description When no auth user is configured, a parser fast path designed for standard client connections may incorrectly apply to...

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...