CVE-2026-16618Network attack vector

Unauthenticated RCE via attacker-controlled upload extension

Published Aug 4, 2026 · Updated Aug 4, 2026

Arbitrary file upload in Improve SEO through 2.0.11 allows remote attackers to execute PHP code without authentication. The upload handler validates only the supplied content type, preserves the attacker-controlled filename extension, and writes the file into a web-accessible directory. A crafted PHP upload can therefore be requested through the web server and execute with the WordPress site's PHP process privileges.

CVSS severity9.8
Critical
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Arbitrary file upload in Improve SEO through 2.0.11 allows remote attackers to execute PHP code without authentication. The upload handler validates only the supplied content type, preserves the attacker-controlled filename extension, and writes the file into a web-accessible directory. A crafted PHP upload can therefore be requested through the web server and execute with the WordPress site's PHP process privileges.

The record

CVE
CVE-2026-16618
Published
Aug 4, 2026
Updated
Aug 4, 2026
Vendor
Nathan Garnett
Product
Improve SEO
Classifications
CWE-434, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=2.0.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nathan Garnett · Improve SEOversion=0 <=2.0.11

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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