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 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.
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-4g68-3pwx-5vfj
- https://github.com/nats-io/nats-server/commit/297b166be60fe13144084eed4b25201ead03204a
- https://github.com/nats-io/nats-server/commit/34b09657bb596d5f850eaa5cfc97ea6b2f989a97
- https://github.com/nats-io/nats-server/releases/tag/v2.12.12
- https://github.com/nats-io/nats-server/releases/tag/v2.14.3