CVE-2026-58214

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

Published: Jul 8, 2026Updated: Jul 13, 2026 Sources: CVE List NVDCWE-863

4.3MEDIUM

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:LPrivileges Required

Low

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:LConfidentiality

Low

I:NIntegrity

None

A:NAvailability

None

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Weaknesses

CWE-863

Affected Products

nats-io

oss-project

nats-serverOn-prem

Databases / cache-message-queue

linuxfoundation

oss-project·USaka pytorch, yocto, everest

nats-serverOn-premDatabase

AI / ML / vector-db-rag

Exploitability

Official Patch Available

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques

Initial Access

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References

https://github.com/nats-io/nats-server/security/advisories/GHSA-4g68-3pwx-5vfj

github.com

https://github.com/nats-io/nats-server/commit/297b166be60fe13144084eed4b25201ead03204a

github.com

https://github.com/nats-io/nats-server/commit/34b09657bb596d5f850eaa5cfc97ea6b2f989a97

github.com

and 2 more references View all →

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