Medium severity · published Mar 24, 2026
CVE-2026-33215
NATS is vulnerable to MQTT hijacking via Client ID
6.5
CVSS
0.2%
EPSS
No
On KEV
Description
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server provides an MQTT client interface. Prior to versions 2.11.15 and 2.12.5, Sessions and Messages can by hijacked via MQTT Client ID malfeasance. Versions 2.11.15 and 2.12.5 patch the issue. No known workarounds are available.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 16% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NA
nats-server · nats-io
< 2.11.15; >= 2.12.0-RC.1, < 2.12.6 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33215
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33215
Broken Link
https://advisories.nats.io/CVE/secnote-2026-06.tx
Vendor Advisory
https://github.com/nats-io/nats-server/security/advisories/GHSA-fcjp-h8cc-6879
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