Medium severity · published Jul 8, 2026
CVE-2026-58254
NATS Server: Incomplete fix for CVE-2026-33249: Leaf node connections bypass Nats-Trace-Dest permission check
6.5
CVSS
0.3%
EPSS
No
On KEV
Description
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.8, message trace destination checks were applied to ordinary client connections but not consistently to messages arriving through leafnode connections, allowing a leafnode operator to send trace events to subjects that would not otherwise be permitted and to use trace-only behavior to prevent normal delivery or storage of affected messages. This issue is fixed in versions 2.14.3 and 2.12.8.
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)0.3% · higher than 23% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NA
nats-server · nats-io
< 2.12.8; >= 2.14.0-RC.1, < 2.14.3 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-58254
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-58254
Patch
https://github.com/nats-io/nats-server/commit/cbe845932980b71563efac5cfa4cc751c88936cd
Release Notes
https://github.com/nats-io/nats-server/releases/tag/v2.12.8
Release Notes
https://github.com/nats-io/nats-server/releases/tag/v2.14.3
Vendor Advisory
https://github.com/nats-io/nats-server/security/advisories/GHSA-p3j5-5hrq-p75h
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