CVE-2026-33217 — Security Box Score

CVE · referencelatest edition

Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-33217MEDIUM

nats-io nats-server — NATS allows MQTT clients to bypass ACL checks

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  L  L  N    6.5   .0026   17.8     —

AFFECTED
  Product      Versions     Fixed
  nats-server  < 2.11.15 –  —

TIMELINE
  Mar 17  Reserved by GitHub_M
  Mar 25  Published (CNA: GitHub_M)
  Aug 17  RESCORED — CVE-2026-33217 (nats-io nats-server). CVSS 7.1 → 6.5 (NVD).

CWE-863 · CNA: GitHub_M · CVSS v3.1 · 8 references · NVD status: Modified

Description

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, when using ACLs on message subjects, these ACLs were not applied in the `$MQTT.>` namespace, allowing MQTT clients to bypass ACL checks for MQTT subjects. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
March 17, 2026	Reserved	Reserved by GitHub_M
March 25, 2026	Published	Published (CNA: GitHub_M)
August 17, 2026	RESCORED	RESCORED — CVE-2026-33217 (nats-io nats-server). CVSS 7.1 → 6.5 (NVD).

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
nats-io	nats-server	—	< 2.11.15	—

Weaknesses

CWE-863

References (8)

https://access.redhat.com/errata/RHSA-2026:21769 [vendor-advisory, x_refsource_REDHAT]
https://access.redhat.com/errata/RHSA-2026:22347 [vendor-advisory, x_refsource_REDHAT]
https://access.redhat.com/errata/RHSA-2026:23345 [vendor-advisory, x_refsource_REDHAT]
https://access.redhat.com/security/cve/CVE-2026-33217 [vdb-entry, x_refsource_REDHAT]
https://advisories.nats.io/CVE/secnote-2026-07.txt [x_refsource_MISC]
https://bugzilla.redhat.com/show_bug.cgi?id=2451446 [issue-tracking, x_refsource_REDHAT]
https://github.com/nats-io/nats-server/security/advisories/GHSA-jxxm-27vp-c3m5 [x_refsource_CONFIRM]
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33217.json [x_sadp-csaf-vex]

Authoritative record: CVE-2026-33217 at cve.org

Vendors: nats-io

Weaknesses: CWE-863

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-33217 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.