CVE-2026-33223
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 · uneditedNATS-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, the NATS message header `Nats-Request-Info:` is supposed to be a guarantee of identity by the NATS server, but the stripping of this header from inbound messages was not fully effective. An attacker with valid credentials for any regular client interface could thus spoof their identity to services which rely upon this header. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.
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 confidenceIn NATS-Server versions prior to 2.11.15 and 2.12.6, the `Nats-Request-Info:` header—which the server uses to guarantee client identity—was not being fully stripped from inbound messages. An authenticated attacker with valid client credentials could exploit this incomplete stripping to spoof their identity when communicating with services that rely on this header for authentication decisions.
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< 2.11.15>= 2.12.0, < 2.12.6CVSS 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
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/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 checksWork through these to decide whether this CVE applies to you.
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Check NATS-Server versionRun `nats-server --version` or `nats-server -v` to display the installed NATS-Server versionAffected if Version is less than 2.11.15 OR version is 2.12.0 through 2.12.5 (inclusive)
If the installed NATS-Server version is 2.11.x below 2.11.15, or 2.12.x below 2.12.6, the incomplete header stripping flaw is present.
Generated from the published advisory. Verify against your own configuration.
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 · scoped2.11.152.12.6
Upgrade NATS-Server to version 2.11.15 or 2.12.6. No workarounds are available, so immediate patching is required.
NATS Server 2.11.15 or 2.12.6 (or later stable release)
- 1. Identify your current NATS Server version by running 'nats-server --version' or checking your deployment configuration
- 2. Determine which release branch you're currently using (2.11.x or 2.12.x)
- 3. For 2.11.x branch users: Upgrade to version 2.11.15 or later
- 4. For 2.12.x branch users: Upgrade to version 2.12.6 or later
- 5. Download the appropriate release from the official NATS GitHub releases page: https://github.com/nats-io/nats-server/releases
- 6. Backup your current NATS Server configuration and any persistent data
- 7. Stop the running NATS Server instance
- 8. Replace the NATS Server binary with the upgraded version
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation4.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,504.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-33223 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-33223 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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