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, 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Linuxfoundation | Nats-Server | < 2.12.12 |
Related Weaknesses (CWE)
References
- https://github.com/nats-io/nats-server/commit/181b1f51f40b9954c57e9d478e051fb257Patch
- https://github.com/nats-io/nats-server/commit/1c429b6fdc5afd4188cc5faf1127f63348Patch
- https://github.com/nats-io/nats-server/releases/tag/v2.12.12Release Notes
- https://github.com/nats-io/nats-server/releases/tag/v2.14.3Release Notes
- https://github.com/nats-io/nats-server/security/advisories/GHSA-7qmq-8cc4-hxwgVendor Advisory
FAQ
What is CVE-2026-58209?
CVE-2026-58209 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, MQTT retained message delivery and QoS1+ durable replay could deliver mes...
How severe is CVE-2026-58209?
CVE-2026-58209 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-2026-58209?
Check the references section above for vendor advisories and patch information. Affected products include: Linuxfoundation Nats-Server.