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Unrestricted File UploadWeakness · CWE-434

CVE-2026-9227

HIGH · 8.8 CVSS v3.1 Published 2026-05-28
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click Patch available

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
The GutenBee – Gutenberg Blocks plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 2.20.1 via the gutenbee_file_and_ext_json function. This is due to a flawed strpos() substring check that only verifies whether the filename contains the string '.json' rather than confirming the filename ends with a .json extension, allowing double-extension filenames like shell.json.php to bypass validation. This makes it possible for authenticated attackers, with author-level access and above, to upload files that may be executable, which makes remote code execution possible.

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
How this class of weakness works · CWE-434

The application accepts uploaded files without properly checking their type or content, so an attacker can upload something executable. If it lands where the server will run it, that is remote code execution. Remediating it means validating content rather than just the extension, storing uploads outside the web root, and never executing them.

General guidance for the unrestricted file upload class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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
High
Availability
High

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

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
Patch available Apply the vendor patch
Vendor patch github.com →
Recommended fix Moderate confidence

Check WordPress plugin repository for version newer than 2.20.1, or apply vendor commit bde934cdecf67a4de1d6548cc1fc6c59bc6690e5

  1. 1. Navigate to the WordPress admin dashboard and locate the GutenBee plugin under Plugins.
  2. 2. Check the currently installed version of the GutenBee plugin (should be 2.20.1 or earlier based on the vulnerability description).
  3. 3. Navigate to Plugins > Add New > Upload Plugin to attempt uploading a newer version if available, or check the WordPress plugin repository for an updated version.
  4. 4. Alternatively, manually apply the fix from the vendor commit at https://github.com/cssigniter/gutenbee/commit/bde934cdecf67a4de1d6548cc1fc6c59bc6690e5 which corrects the strpos() check to properly validate that the filename ends with '.json' extension rather than just containing the string '.json'.
  5. 5. After applying the patch or upgrading, verify the fix by attempting to upload a double-extension file (e.g., shell.json.php) through the vulnerable function to confirm the attack is no longer possible.
  6. 6. Ensure the site is tested thoroughly after the fix is applied.

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

We can apply and verify the patch for your build — typical engagement from $3,200. Get the patch applied

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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-2026-9227 in production — separate from our analysis above.

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