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Fencer Intel
medium 4.3

CVE-2026-33249 json

NATS: Message tracing can be redirected to arbitrary subject

published 7mo ago modified last mo. also BIT-nats-2026-33249 , EUVD-2026-16000 , GHSA-8m2x-3m6q-6w8j , GO-2026-4826

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/nats-io/nats-server/v2 2.11.15, 2.12.6
  • bitnami nats 2.11.15, 2.12.6
  • linuxfoundation nats-server 2.11.15, 2.12.6
  • nats nats_server 2.11.15, 2.12.6
  • nats nats_streaming_server 2.11.15, 2.12.6
  • nats-server Debian 14 2.12.6-1

debian advisories DEBIAN-CVE-2026-33249

  • govulncheck-vulndb openSUSE Leap 15.6 0.0.20260326T203309-150000.1.155.2

suse advisories SUSE-SU-2026:1135-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

  • nats-server Alpine 3.24, Alpine 3.23 2.12.6-r0

alpine advisories ALPINE-CVE-2026-33249

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-33249 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-33249 updated cvss 6.4

github.com/nats-io/nats-server: NATS-Server: Unauthorized trace message redirection via message tracing headers

  • Red Hat Multicluster Global Hub multicluster-globalhub/multicluster-globalhub-grafana-rhel9 Red Hat OpenShift Container Platform 4 openshift4/oc-mirror-plugin-rhel9
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
7mo ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
OSV 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
go github.com/nats-io/nats-server/v2
>=2.11.0, <2.11.15
>=2.12.0-preview.1, <2.12.6
2.11.15
2.12.6
bitnami nats
>=2.11.0, <2.11.15
>=2.12.0, <2.12.6
2.11.15
2.12.6
go github.com/nats-io/nats-server
all versions
 no fix listed

Affected products

  • nats-io nats-server

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.