CVE-2026-58211 json
NATS Server: `no_auth_user` pre-CONNECT fast path bypasses user connection restrictions
published 2026-07-08 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-42390
- cvss
- 5.4
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 21%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- linuxfoundation nats-server 2.12.12, 2.14.3
- nats-server Debian 14 2.14.3-1
debian advisories DEBIAN-CVE-2026-58211
- nats-server2.12 hummingbird 1 2.12.12-1.hum1
- nats-server2.14 hummingbird 1 2.14.3-1.hum1
red hat advisories RHSA-2026:36017RHSA-2026:36016
Vendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2026-58211 updated cvss 6.5
nats-server: NATS Server: Authentication bypass allows unauthorized access and information disclosure
-
Red Hat Hardened Images nats-server2.14 2.14.3-1.hum1, nats-server2.12 2.12.12-1.hum1fixed: vendor fix RHSA-2026:36017
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 4 mo ago
Exploit prediction
0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.4 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N |
Affected products
- nats-io nats-server
Classification
- Weakness
-
- CWE-863 Incorrect Authorization
References
-
github.com
/nats-io/nats-server/security/advisories/GHSA-hmmp-q8cx-v964
mitigation, vendor-advisory
Sources
- CVE List CVE-2026-58211
- NVD CVE-2026-58211
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.