CVE-2026-58253
NATS Server: Route API Auth Bypass
8.8
HIGH
CVSS 3.1
EPSS 0.37%
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.
How to fix CVE-2026-58253
To remediate CVE-2026-58253, upgrade the affected package to a fixed version below.
- —upgrade to 2.11.16 or later
Is CVE-2026-58253 being exploited?
Low — EPSS is 0.4%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 2.11.16, >= 2.12.0, < 2.12.6
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH8.8 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L |