How severe is CVE-2026-33217?

CVE-2026-33217 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity high, and availability none.

Is CVE-2026-33217 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33217?

CVE-2026-33217 affects Linuxfoundation Nats-server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33217?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-33217 have an EU (EUVD) identifier?

Yes. CVE-2026-33217 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-15966.

When was CVE-2026-33217 published?

CVE-2026-33217 was published on 2026-03-25 and last updated on 2026-06-30.

CVE-2026-33217

CVE-2026-33217 is a high-severity vulnerability in Linuxfoundation Nats-server with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.

Key facts

Severity: High (CVSS 3.x base score 7.1)
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-15966
Weakness: CWE-863
Affected product: Linuxfoundation Nats-server
Published: 2026-03-25
Last modified: 2026-06-30

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.

Frequently asked questions

What is CVE-2026-33217?: 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.
How severe is CVE-2026-33217?: CVE-2026-33217 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity high, and availability none.
Is CVE-2026-33217 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33217?: CVE-2026-33217 affects Linuxfoundation Nats-server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33217?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-33217 have an EU (EUVD) identifier?: Yes. CVE-2026-33217 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-15966.
When was CVE-2026-33217 published?: CVE-2026-33217 was published on 2026-03-25 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*

More vulnerabilities in Linuxfoundation Nats-server

CVE-2022-28357 — Critical (CVSS 9.8): NATS nats-server 2.2.0 through 2.7.4 allows directory traversal because of an unintended path to a management action…
CVE-2020-26892 — Critical (CVSS 9.8): The JWT library in NATS nats-server before 2.1.9 has Incorrect Access Control because of how expired credentials are…
CVE-2022-24450 — High (CVSS 8.8): NATS nats-server before 2.7.2 has Incorrect Access Control. Any authenticated user can obtain the privileges of the…
CVE-2026-33216 — High (CVSS 8.6): NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions…
CVE-2026-33218 — High (CVSS 7.5): NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions…
CVE-2026-29785 — High (CVSS 7.5): NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions…

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