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 unauthenticated MQTT client could cause the server to retain large incomplete MQTT CONNECT packets before authentication completed, consuming server memory while the parser waited for the advertised MQTT packet length. This issue is fixed in versions 2.14.3 and 2.12.12.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| nats-io | nats-server | < 2.12.12, >= 2.14.0-RC.1, < 2.14.3 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | nats-server | 2.14.3-1 | — |
| Debian 13 | nats-server | No fix yet | — |
| Debian 12 | nats-server | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | nats-server | No fix yet | — |
| Ubuntu 25.10 | nats-server | No fix yet | — |
| Ubuntu 24.04 LTS | nats-server | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | nats-server | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | nats-server2.12 | 2.12.12-1.hum1 | RHSA-2026:36017 |
| Red Hat Hardened Images 1 | nats-server2.14 | 2.14.3-1.hum1 | RHSA-2026:36016 |
Advisories 3
- RHSA-2026:36017 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Sep 8, 2026
- RHSA-2026:36016 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Sep 6, 2026
- WID-SEC-2026-2132 NATS Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jul 14, 2026
References
- https://github.com/nats-io/nats-server/security/advisories/GHSA-r72h-j7qq-v6qg
- https://github.com/nats-io/nats-server/commit/bce9ef39469e610aeddb819194ceb7f7edfc0861
- https://github.com/nats-io/nats-server/commit/e016e47bbf70304945f2ae9dc397e4862adefaf5
- https://github.com/nats-io/nats-server/releases/tag/v2.12.12
- https://github.com/nats-io/nats-server/releases/tag/v2.14.3