CVE-2026-33249 NATS: Message tracing can be redirected to arbitrary subject
A valid NATS client can redirect message traces to unauthorized subjects, bypassing publish permissions and potentially exposing trace data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33249?
CVE-2026-33249 is a medium-severity missing authorization vulnerability in nats-io nats-server, published on 25 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.11.0 and prior to versions 2.11.15 and 2.12.6, a valid client which uses message tracing headers can indicate that the trace messages can be sent to an arbitrary valid subject, including those to which the client does not have publish permission. The payload is a valid trace message and not chosen by the attacker. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.
Weakness: CWE-863
Which versions are affected by CVE-2026-33249?
7 open source packages ship an affected version, including github.com/nats-io/nats-server/v2, nats and github.com/nats-io/nats-server. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/nats-io/nats-server/v2 Go | From 2.11.0 | 2.11.15, 2.12.6 |
github.com/nats-io/nats-server/v2 Go | From 2.11.0 | 2.11.15 |
github.com/nats-io/nats-server/v2 Go | From 2.11.0 | 2.11.15 |
github.com/nats-io/nats-server/v2 Go | From 2.12.0-preview.1 | 2.12.6 |
github.com/nats-io/nats-server/v2 Go | From 2.12.0-preview.1 | 2.12.6 |
nats Bitnami | From 2.11.0 | 2.11.15, 2.12.6 |
1 more packages
github.com/nats-io/nats-server Go | All versions | None |
Products include Linuxfoundation Nats-Server.
How do I fix CVE-2026-33249?
Upgrade github.com/nats-io/nats-server/v2 to a fixed version for your release line: 2.11.15 or 2.12.6.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-33249 being exploited?
There is no known exploitation of CVE-2026-33249 in the wild and no public exploit code.
Other vulnerabilities in nats-io nats-server
- CVE-2022-28357 NATS nats-server allows directory traversal via unintended path to a management action
- CVE-2026-58253 NATS Server: Route API Auth Bypass
- CVE-2022-24450 Incorrect Authorization in NATS nats-server
- CVE-2026-33216 NATS has MQTT plaintext password disclosure
- CVE-2026-58207 NATS Server: Remote crash via integer overflow in Connz pagination
Sources
Also known as BIT-nats-2026-33249, CLEANSTART-2026-QF31649, DEBIAN-CVE-2026-33249, GHSA-8m2x-3m6q-6w8j, GO-2026-4826, MINI-6jvx-c2r8-227h and 8 more.