Medium severity · published Mar 25, 2026
CVE-2026-33249
NATS: Message tracing can be redirected to arbitrary subject
4.3
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. Starting in version 2.11.0 and prior to versions 2.11.15 and 2.12.6, a valid client which uses message tracing headers can indicate that the trace messages can be sent to an arbitrary valid subject, including those to which the client does not have publish permission. The payload is a valid trace message and not chosen by the attacker. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 15% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NA
nats-server · nats-io
>= 2.11.0, < 2.11.15; >= 2.12.0-preview.1, < 2.12.6 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33249
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33249
Vendor Advisory
https://advisories.nats.io/CVE/secnote-2026-15.txt
Vendor Advisory
https://github.com/nats-io/nats-server/security/advisories/GHSA-8m2x-3m6q-6w8j
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