6.4

CVE-2026-33246: linuxfoundation nats-server Improper Authentication

CVSS: 6.4v3.1MediumAnalyzed
AliasesUBUNTU-CVE-2026-33246DEBIAN-CVE-2026-33246CGA-3x6g-hrhj-8x7m
Published 25-03-2026Last modified 28-03-2026
Open JSON

Vulnerability summary

CVE-2026-33246 is a medium (CVSS 6.4) Improper Authentication 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 · +0.10 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-4CWQ-R926-CXPV

Timeline

  1. 25-03-2026
    PublishedVulnerability first disclosed.
  2. 28-03-2026
    Last modifiedVulnerability information updated.

Description

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough information to allow for account/user identification, such that NATS clients could make their own decisions on how to trust a message, provided that they trust the nats-server as a broker. A leafnode connecting to a nats-server is not fully trusted unless the system account is bridged too. Thus identity claims should not have propagated unchecked. Prior to versions 2.11.15 and 2.12.6, NATS clients relying upon the Nats-Request-Info: header could be spoofed. This does not directly affect the nats-server itself, but the CVSS Confidentiality and Integrity scores are based upon what a hypothetical client might choose to do with this NATS 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

+0.10 pp

From 0.14% on 20-09-2026

20-09-202620-10-2026
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