CVE-2026-58253: Linuxfoundation Nats-Server

High severity, CVSS 8.8. EPSS: 0.4% chance of exploitation in the next 30 days.

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.

Affected products

• Linuxfoundation Nats-Server: before 2.11.16 (fixed in 2.11.16); from 2.12.0, before 2.12.7 (fixed in 2.12.7)

Published 2026-07-08. Last modified 2026-07-13.