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CVE-2026-33249· NVD / CVE Program· CNA GitHub_M

NATS: Message tracing can be redirected to arbitrary subject

Noroxi assessment

Priority: Monitor (action score 17/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.27% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: nats-server (Debian:14) 2.12.6-1; github.com/nats-io/nats-server/v2 (Go) 2.11.15, 2.12.6.

Low priority for now. Upgrade to nats-server (Debian:14) 2.12.6-1; github.com/nats-io/nats-server/v2 (Go) 2.11.15, 2.12.6 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 4.3 · v3.1—No exploit Fix available
Published
Mar 25, 2026
Updated
Jun 17, 2026
EPSS
0.2% · 18th percentile

Report tools

JSON

Action score

17

Monitor

Low priority for now.

CVSS
17 / 40 · 4.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
4.3
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxfoundationnats-server

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linuxfoundation nats-server2.11.0 and later · before 2.11.15
  • linuxfoundation nats-server2.12.0 and later · before 2.12.6

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • nats-io nats-server

    • >= 2.11.0, < 2.11.15, >= 2.12.0-preview.1, < 2.12.6affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:14nats-serverbefore 2.12.6-12.12.6-1
Gogithub.com/nats-io/nats-serverfrom 0—
Gogithub.com/nats-io/nats-server/v2from 2.11.0 · before 2.11.152.11.15
Gogithub.com/nats-io/nats-server/v2from 2.12.0-preview.1 · before 2.12.62.12.6

Same product

linuxfoundation: all records

Other highest-scoring records for the same primary product.

  • CVE-2020-26892The JWT library in NATS nats-server before 2.1.9 has Incorrect Access Control because of how expired credentials are handled.
    40Plan
  • CVE-2022-28357NATS nats-server 2.2.0 through 2.7.4 allows directory traversal because of an unintended path to a management action from a management accou
    39Monitor
  • CVE-2026-58253NATS Server: Route API Auth Bypass
    35Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-33223Mar 25, 2026 · NATS Server: Incomplete Stripping of Nats-Request-Info Header Allows Identity Spoofing
    21Monitor
  • ← EarlierCVE-2026-33248Mar 25, 2026 · NATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching
    16Monitor
  • Later →CVE-2026-58209Jul 8, 2026 · NATS Server: MQTT retained and QoS replay bypass subscribe deny filters
    17Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:nats-server2.12.6-1 · Debian:14Package registry (OSV)
Go:github.com/nats-io/nats-server/v22.11.15Package registry (OSV)
Go:github.com/nats-io/nats-server/v22.12.6Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-332170 days apartNATS allows MQTT clients to bypass ACL checks
    26Monitor
  • CVE-2026-58211105 days apartNATS Server: `no_auth_user` pre-CONNECT fast path bypasses user connection restrictions
    21Monitor
  • CVE-2026-58254105 days apartNATS Server: Incomplete fix for CVE-2026-33249: Leaf node connections bypass Nats-Trace-Dest permission check
    21Monitor
  • CVE-2026-58209105 days apartNATS Server: MQTT retained and QoS replay bypass subscribe deny filters
    17Monitor
  • CVE-2026-58214105 days apartNATS Server: MQTT subscribe ACL bypass via $MQTT.deliver.pubrel prefix (incomplete fix for CVE-2026-33217)
    17Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-863 · Incorrect Authorization

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records