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MEDIUM · 4.3

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.delive...

Vulnerability 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.

CVSS Score

4.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE

Affected Products

VendorProductVersions
LinuxfoundationNats-Server< 2.12.12

Related Weaknesses (CWE)

CWE-863

References

FAQ

What is CVE-2026-58214?

CVE-2026-58214 is a vulnerability with a CVSS score of 4.3 (MEDIUM). 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.delive...

How severe is CVE-2026-58214?

CVE-2026-58214 has been rated MEDIUM with a CVSS base score of 4.3/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-58214?

Check the references section above for vendor advisories and patch information. Affected products include: Linuxfoundation Nats-Server.