CVE-2026-58253: linuxfoundation nats-server Improper Authentication
Vulnerability summary
CVE-2026-58253 is a high (CVSS 8.8) Improper Authentication vulnerability in linuxfoundation nats-server. EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 29.2% of scored vulnerabilities.
Timeline
- 08-07-2026PublishedVulnerability first disclosed.
- 09-07-2026Last modifiedVulnerability information updated.
Description
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, when no_auth_user was configured, a parser fast path intended for ordinary client connections could also apply to route or leafnode listeners, allowing an unauthenticated peer to bypass inter-server CONNECT authentication and operate with the privileges associated with that connection type. This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated8.8HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L
- OSV · DebianEcosystem advisory · calculated8.8HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L
- NVDNIST8.8HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L
EPSS trend
Probability
0.37%
Chance of exploitation in the next 30 days
Percentile
29%
Versus all other CVEs
30-day change
0.00 pp
From 0.37% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Debian1 product
- nats-serverAll versions (No fix recorded) | < 2.14.1-1
Linuxfoundation1 product
- nats-server< 2.11.16 | ≥ 2.12.0, < 2.12.7
Nats-io1 product
- nats-server< 2.11.16 | ≥ 2.12.0-preview.1, < 2.12.6
Ubuntu1 product
- nats-serverAll versions (No fix recorded)
4 vendors · 4 products
References
11 links- github.com/nats-io/nats-server/security/advisories/GHSA-38x3-76xf-cq45X Refsource CONFIRMREPORTVendor Advisory
