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Nats ServerApplication · Linuxfoundation

CVE-2023-47090

MEDIUM · 6.5 CVSS v3.1 Published 2023-10-30
Fix available
A fix is available. Upgrade to 2.9.23 / 2.10.2 or later.
See remediation →
71/100
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 nats-server before 2.9.23 and 2.10.x before 2.10.2 has an authentication bypass. An implicit $G user in an authorization block can sometimes be used for unauthenticated access, even when the intention of the configuration was for each user to have an account. The earliest affected version is 2.2.0.

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

NATS nats-server versions 2.2.0 through 2.9.22 and 2.10.0-2.10.1 contain an authentication bypass where an implicit $G (default) user in an authorization block can allow unauthenticated access, even when the configuration intent was for all users to require authentication.

MitigationUpgrade to nats-server version 2.9.23, 2.10.2, or later. Review and explicitly configure authorization blocks to ensure the implicit $G user is properly handled or disabled if all users should require authentication.

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:>= 2.2.0, < 2.9.23>= 2.10.0, < 2.10.2

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
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/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. Determine nats-server version
    Run 'nats-server --version' or check the binary version
    Affected if Version is 2.2.0 through 2.9.22 or 2.10.0-2.10.1 (compare your installed version to the affected ranges)
  2. Locate nats-server configuration file
    Check for config file at /etc/nats-server.conf or ~/nats-server.conf, or look for config specified via 'nats-server -c <path>'
    Affected if Configuration file exists and is in use
  3. Inspect authorization block in configuration
    Search the config file for an 'authorization' block or stanza
    Affected if An authorization block is defined in the configuration
  4. Check for $G user in authorization block
    Within the authorization block, look for a user entry named '$G' or 'default_user' (the implicit $G user)
    Affected if The $G user is defined within an authorization block, which can permit unauthenticated access

You are affected if you run a vulnerable nats-server version AND your configuration contains an authorization block that includes the implicit $G user, allowing unauthenticated access despite configuration intent for authenticated-only access.

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 2.9.23 / 2.10.2 or later
Fixed in 2.9.232.10.2
Interim mitigation

Upgrade to nats-server version 2.9.23, 2.10.2, or later. Review and explicitly configure authorization blocks to ensure the implicit $G user is properly handled or disabled if all users should require authentication.

Recommended fix High confidence

NATS Server 2.9.23 or 2.10.2 (or later stable release)

  1. 1. Back up your current NATS server configuration and data
  2. 2. Stop the NATS server service
  3. 3. Download the fixed version (2.9.23 or 2.10.2 or later) from the official NATS releases (github.com/nats-io/nats-server/releases)
  4. 4. Install the new version following standard installation procedures for your platform
  5. 5. Restore your configuration ensuring proper user account definitions
  6. 6. Start the NATS server and verify authentication is working as expected
  7. 7. Test that unauthenticated access is no longer possible
Caveat Review release notes for any breaking changes between your current version and the target version

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
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

Scan for this in your stack

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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-2023-47090 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