CVE-2026-58211NATS Server: `no_auth_user` pre-CONNECT fast path bypasses user connection restrictions
Updated under an hour ago ()
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It affects nats-io nats-server and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, a client could be registered as the configured no_auth_user through a parser path used when the first client operation was not CONNECT, bypassing user-level connection restrictions such as allowed_connection_types or proxy_required that normal authentication would apply. This issue is fixed in versions 2.14.3 and 2.12.12.
- CVSS
- 5.4 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
- Weakness (CWE)
- CWE-863
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Analyzed
- Record last updated
- Jul 9, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
nats-io nats-server nats_io:nats_server (from the name) | before 2.12.12; from 2.14.0-RC.1, < 2.14.3 | CNA record |
linuxfoundation nats-server linuxfoundation:nats-server | from 2.12.0 before 2.12.12; from 2.14.0 before 2.14.3 | NVD |
References
- https://github.com/nats-io/nats-server/security/advisories/GHSA-hmmp-q8cx-v964x-refsource-confirm, mitigation, vendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.