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4.3 Medium

CVE-2026-58214 NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system

Description

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 protocol metadata for sessions in the account. This issue is fixed in versions 2.14.3 and 2.12.12.

Affected products and versions

Product Affected versions Fixed in
nats-server 2.14 2.14.0-RC.1 → < 2.14.3 2.14.3
nats-server 2.12 earliest → < 2.12.12 2.12.12

References

Timeline

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