NATS Server: MQTT subscribe ACL bypass via $MQTT.deliver.pubrel prefix (incomplete fix for CVE-2026-33217) (nats-io nats-server)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.35 % · percentile 29 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
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.
Weaknesses (CWE)
- CWE-863 — Incorrect Authorization
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
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 4.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N | GitHub_M |
| CVSS 3.1 | MEDIUM 4.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N | NVD · security-advisories@github.com (Secondary) |
European references
- ENISA EUVD · EUVD-2026-42387
- GCVE · GCVE-0-2026-58214
Affected configurations (NVD CPE)
cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*< 2.12.12cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*≥ 2.14.0 < 2.14.3
Affected products
| Product | Versions |
|---|---|
| nats-io · nats-server | affected < 2.12.12 ; affected >= 2.14.0-RC.1, < 2.14.3 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |