Vulnerability · Published Mar 25, 2026 · Assigned by GitHub_M
CVE-2026-33223NATS Server: Incomplete Stripping of Nats-Request-Info Header Allows Identity Spoofing
Medium 6.4
In plain English
A medium-severity authentication bypass by spoofing in nats-server from nats-io. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, the NATS message header `Nats-Request-Info:` is supposed to be a guarantee of identity by the NATS server, but the stripping of this header from inbound messages was not fully effective. An attacker with valid credentials for any regular client interface could thus spoof their identity to services which rely upon this header. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | nats-server | 2.12.6-r0 | ALPINE-CVE-2026-33223 |
| Alpine:v3.24 | nats-server | 2.12.6-r0 | ALPINE-CVE-2026-33223 |
| Debian:12 | nats-server | no fix listed | DEBIAN-CVE-2026-33223 |
| Debian:13 | nats-server | no fix listed | DEBIAN-CVE-2026-33223 |
| Debian:14 | nats-server | 2.12.6-1 | DEBIAN-CVE-2026-33223 |
| Go | github.com/nats-io/nats-server | no fix listed | GHSA-pwx7-fx9r-hr4h |
| Go | github.com/nats-io/nats-server | no fix listed | GO-2026-4835 |
| Go | github.com/nats-io/nats-server/v2 | 2.11.15, 2.12.6 | GO-2026-4835 |
| Go | github.com/nats-io/nats-server/v2 | 2.11.15 | GHSA-pwx7-fx9r-hr4h |
| Go | github.com/nats-io/nats-server/v2 | 2.12.6 | GHSA-pwx7-fx9r-hr4h |
| Ubuntu:24.04:LTS | nats-server | no fix listed | UBUNTU-CVE-2026-33223 |
| Ubuntu:25.10 | nats-server | no fix listed | UBUNTU-CVE-2026-33223 |
| Ubuntu:26.10 | nats-server | no fix listed | UBUNTU-CVE-2026-33223 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| nats-io | nats-server | < 2.11.15>= 2.12.0-RC.1, < 2.12.6 |
Weakness: CWE-290 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
References
- https://github.com/nats-io/nats-server/security/advisories/GHSA-pwx7-fx9r-hr4h x_refsource_CONFIRM
- https://advisories.nats.io/CVE/secnote-2026-09.txt x_refsource_MISC