Subject: nats-server: JetStream: Stream restore endpoint auth bypass

NATS-advisory-ID: 2026-12
Aliases: CVE-2026-33222, GHSA-9983-vrx2-fg9c
Date: 2026-03-24
Fixed-In: 2.12.6, 2.11.15

Background:

NATS.io is a high performance open source pub-sub distributed communication
technology, built for the cloud, on-premise, IoT, and edge computing.

The persistent storage feature, JetStream, has a management API which
has many features, amongst which are backup and restore.


Problem Description:

Users with JetStream admin API access to restore one stream could
restore to other stream names, impacting data which should have been
protected against them.


Affected Versions:

 nats-server: any version before v2.12.6 or v2.11.15


Workarounds:

If you have Users who have limited JetStream restore permissions,
temporarily remove those permissions.


References:

 * This document is canonically:
   <https://advisories.nats.io/CVE/secnote-2026-12.txt>
 * GHSA advisory:
   <https://github.com/nats-io/nats-server/security/advisories/GHSA-9983-vrx2-fg9c>
 * MITRE CVE entry:
   <https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-33222>