CVE-2026-58209CWE-863

NATS Server: MQTT retained and QoS replay bypass subscribe deny filters

Medium · published July 8, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
26.5
In the wild
Unconfirmed
What it is

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, MQTT retained message delivery and QoS1+ durable replay could deliver messages whose original topics matched a subscriber configured subscribe deny rule because these delivery paths did not consistently recheck the concrete original topic before sending the MQTT PUBLISH to the subscriber. This issue is fixed in versions 2.14.3 and 2.12.12.

The record
Technical detail
CVSS v3.1
4.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00342 · 26.5th percentile
Weakness
CWE-863 · Incorrect Authorization
Published
2026-07-08T20:12Z
EPSS history
Timeline
  • 08 JUL 20:12Z
    NATS Server: MQTT retained and QoS replay bypass subscribe deny filters
    cvelistv5