Arbitrary file upload in Improve Seo

CVE-2026-16618

The Improve SEO WordPress plugin through 2.0.11 does not properly validate uploaded files, checking only the file content type while writing the file with the attacker-supplied extension into a publicly accessible directory, allowing unauthenticated users to upload executable PHP files and achieve remote code execution.

Vulnerability class: Unrestricted File Upload

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.008 (57.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 57.6% 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-2026-16618: held from 0.008 to 0.008.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

  • Improve Seo — versions 0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-16618?
CVE-2026-16618 is a critical-severity vulnerability in Improve Seo, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2026-08-04.
How severe is CVE-2026-16618?
Critical severity. CVSS v3 base score is 9.8 out of 10.