6.4

CVE-2026-33223: linuxfoundation nats-server Authentication Bypass by Spoofing

CVSS: 6.4v3.1MediumAnalyzed
AliasesUBUNTU-CVE-2026-33223DEBIAN-CVE-2026-33223CGA-53h6-v59q-q4cr
Published 25-03-2026Last modified 26-03-2026
Open JSON

Vulnerability summary

CVE-2026-33223 is a medium (CVSS 6.4) Authentication Bypass by Spoofing vulnerability in linuxfoundation nats-server. EPSS estimates a 0.24% chance of exploitation in the next 30 days, higher than 14% of scored vulnerabilities.

Overall risk
26/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.4/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.24%
0%100%
Low · +0.03 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 3
OPENSUSE-SU-2026:21483-1SUSE-SU-2026:1135-1CGA-5PW7-H9G6-P4MX

Timeline

  1. 25-03-2026
    PublishedVulnerability first disclosed.
  2. 26-03-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.24%

Chance of exploitation in the next 30 days

Percentile

14%

Versus all other CVEs

30-day change

+0.03 pp

From 0.21% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.24%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard28 products
  • k3s< 1.35.2.1-r4
  • k3s-1.32< 1.32.13.1-r7
  • k3s-1.33< 1.33.9.1-r6
  • k3s-static< 1.35.2.1-r4
  • k3s-static-1.32< 1.32.13.1-r7
Wolfi12 products
  • k3s< 1.35.2.1-r4
  • k3s-1.32< 1.32.13.1-r7
  • k3s-1.33< 1.33.9.1-r6
  • k3s-static< 1.35.2.1-r4
  • k3s-static-1.32< 1.32.13.1-r7
Debian1 product
  • nats-serverAll versions (No fix recorded) | < 2.12.6-1
Github.com/nats-io1 product
  • nats-serverAll versions (No fix recorded)
Github.com/nats-io/nats-server1 product
  • v2< 2.11.15 | ≥ 2.12.0-RC.1, < 2.12.6
Linuxfoundation1 product
Nats-io1 product
Ubuntu1 product
  • nats-serverAll versions (No fix recorded)

8 vendors · 46 products

References

8 links