CVE-2026-58253

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.

References

• https://github.com/nats-io/nats-server/commit/7b81dd455ea95960090a84858c7662827948d1b6
• https://github.com/nats-io/nats-server/commit/8b8e1ad4ceed32321e00d4fc6e76be05bc13bca6
• https://github.com/nats-io/nats-server/commit/b86147e81710a52b72a7f7275f91d69f723f5cb3
• https://github.com/nats-io/nats-server/releases/tag/v2.11.16
• https://github.com/nats-io/nats-server/releases/tag/v2.12.7