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Nats ServerApplication · Linuxfoundation

CVE-2026-33247

MEDIUM · 5.3 CVSS v3.1 Published 2026-03-25
Fix available
A fix is available. Upgrade to 2.11.15 / 2.12.6 or later.
See remediation →
59/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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, if a nats-server is run with static credentials for all clients provided via argv (the command-line), then those credentials are visible to any user who can see the monitoring port, if that too is enabled. The `/debug/vars` end-point contains an unredacted copy of argv. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, configure credentials inside a configuration file instead of via argv, and do not enable the monitoring port if using secrets in argv. Best practice remains to not expose the monitoring port to the Internet, or to untrusted network sources.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In NATS-Server versions prior to 2.11.15 and 2.12.6, static credentials passed via command-line arguments (argv) are exposed in plain text through the /debug/vars monitoring endpoint. Any user with access to the monitoring port can retrieve unredacted argv data, including sensitive authentication credentials.

MitigationUpgrade to NATS-Server version 2.11.15 or 2.12.6, or migrate credentials from command-line arguments to a configuration file. Additionally, restrict access to the monitoring port to trusted networks only.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Nats ServerApplication
Affected:< 2.11.15>= 2.12.0, < 2.12.6

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify NATS Server version
    Run 'nats-server --version' or check the binary version. Compare against the affected ranges: < 2.11.15 or >= 2.12.0 and < 2.12.6
    Affected if The installed version falls within the vulnerable ranges (< 2.11.15 or >= 2.12.0, < 2.12.6)
  2. Check for credentials in command-line arguments
    Review the process startup script or command used to launch nats-server. Look for --creds, --auth, --user, --password, or similar credential-related flags passed directly in argv
    Affected if Credentials are passed as command-line arguments to the nats-server process
  3. Verify monitoring endpoint is enabled
    Check the NATS Server configuration for 'monitor_port' or 'http' settings, and confirm the server is listening on that port
    Affected if The monitoring endpoint is enabled and accessible on a network port
  4. Confirm credential exposure via /debug/vars
    Make an HTTP request to http://<monitoring_host>:<monitoring_port>/debug/vars and inspect the response for unredacted credential strings that were passed via command line
    Affected if Plain-text credentials appear in the /debug/vars output

You are affected if running a vulnerable version AND credentials were passed via command-line arguments AND the monitoring endpoint is accessible to untrusted users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.11.15 / 2.12.6 or later
Fixed in 2.11.152.12.6
Interim mitigation

Upgrade to NATS-Server version 2.11.15 or 2.12.6, or migrate credentials from command-line arguments to a configuration file. Additionally, restrict access to the monitoring port to trusted networks only.

Recommended fix High confidence

2.11.15 or 2.12.6 (or their respective latest patch releases)

  1. Identify current NATS Server version by running `nats-server --version`
  2. If running 2.11.x branch: Upgrade to version 2.11.15 or later (e.g., 2.11.15, 2.11.16, etc.)
  3. If running 2.12.x branch: Upgrade to version 2.12.6 or later (e.g., 2.12.6, 2.12.7, etc.)
  4. After upgrade, verify the fix by checking that /debug/vars endpoint no longer exposes command-line credentials
  5. As a defense-in-depth measure, ensure the monitoring port is not exposed to untrusted networks

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Nats Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-33247 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data