🛡️ CVE-2026-58209 — nats

🟡 CVSS 5.0 — Medium ✅ No Known Exploit NVD
5.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability none.

Affected software

CVE-2026-58209 is recorded against 2 packages.

  • nats
  • nats-server (from 2.14.0 up to 2.14.3)

Timeline and source

Published on 14 July 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com (Web)
github.com (Web)
github.com (Web)
github.com (Web)
github.com (Web)
nvd.nist.gov (Web)

Details

Severity MEDIUM
CVSS Score 5.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2026-07-14
Updated 2026-08-12
Modified 2026-07-14

Affected Packages

Software From version Fixed in
nats — —
nats-server 2.14.0 2.14.3

Similar Threats

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