BIT-NATS-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...

Incorrect Authorization

Overview github.com/nats-io/nats-server/v2/server is an A simple, secure and performant communications system for digital systems, services and devices. Affected versions of this package are vulnerable to Incorrect Authorization in the subscribe process. An attacker can gain unauthorized access t...

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...