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CVE-2026-33217

MEDIUMCVSS 6.5/10EPSS 0.26%

Last modified

CVE-2026-33217 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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. EPSS estimates a 0.26% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS Probability
0.26%

17.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
LinuxfoundationNats-Server< 2.11.15
LinuxfoundationNats-Server>= 2.12.0, < 2.12.6

References

Timeline

Published
Last Modified
Status
Modified

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 score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.26% probability of exploitation in the next 30 days.
How do I fix CVE-2026-33217?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST