Medium 4.3Published Jul 8, 2026

CVE-2026-58214NATS Server: MQTT subscribe ACL bypass via $MQTT.deliver.pubrel prefix (incomplete fix for CVE-2026-33217)

Updated under an hour ago (Oct 27, 2026, 6:00 PM ET)

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It affects nats-io nats-server and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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: 4.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness (CWE): CWE-863
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jul 9, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

nats-io nats-server nats_io:nats_server (from the name)	before 2.12.12; from 2.14.0-RC.1, < 2.14.3	CNA record
linuxfoundation nats-server linuxfoundation:nats-server	before 2.12.12; from 2.14.0 before 2.14.3	NVD

References

References

https://github.com/nats-io/nats-server/security/advisories/GHSA-4g68-3pwx-5vfj	x-refsource-confirm, vendor-advisory
https://github.com/nats-io/nats-server/commit/297b166be60fe13144084eed4b25201ead03204a	x-refsource-misc, patch
https://github.com/nats-io/nats-server/commit/34b09657bb596d5f850eaa5cfc97ea6b2f989a97	x-refsource-misc, patch
https://github.com/nats-io/nats-server/releases/tag/v2.12.12	x-refsource-misc, release-notes
https://github.com/nats-io/nats-server/releases/tag/v2.14.3	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.