Arbitrary file upload in Cssigniterteam Gutenbee – Gutenberg Blocks

CVE-2026-9227

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.

Vulnerability class: Unrestricted File Upload

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.012 (67.7th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 67.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-9227: rose from 0.007 to 0.012.

EPSS over last 30 days · oldest: 0.007 · newest: 0.012 · change: +0.005

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-9227?
CVE-2026-9227 is a high-severity vulnerability in Cssigniterteam Gutenbee – Gutenberg Blocks, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 8.8/10. Published 2026-05-28.
How severe is CVE-2026-9227?
High severity. CVSS v3 base score is 8.8 out of 10.