CVE-2026-10818

WPForms Pro <= 1.10.1.1 - Unauthenticated Arbitrary File Write via Chunked Upload Init/Finalize Ordering

2026-07-24 17:42
lhking

Strategic Overview

Status
Patched in 2.0.0
Affected Plugin
WPForms Pro
Affected Version
<= 1.10.1.1
CVSS
8.1High
Weakness type
CWE-434 · Unrestricted Upload of File with Dangerous Type
CVE
CVE-2026-10818
View all WPForms Pro vulnerabilities

At a glance

CVE-2026-10818 is a high-severity Unrestricted Upload of File with Dangerous Type vulnerability in the WPForms Pro WordPress plugin, affecting versions <= 1.10.1.1. It carries a CVSS score of 8.1 (reachable over the network; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 2.0.0; sites on affected versions should update now. Disclosed July 2026, reported by lhking.

Vulnerability Overview

The WPForms Pro plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 1.10.1.1 via the ajax_chunk_upload_finalize function. This is due to the file type validation occurring after chunk metadata and file contents have already been written to disk, and the assembled file not being deleted upon validation failure. This makes it possible for unauthenticated attackers to upload files that may be executable, which makes remote code execution possible.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-434: Unrestricted Upload of File with Dangerous Type

Reaching this weakness in WPForms Pro <= 1.10.1.1 takes no account at all. An unrestricted file upload lets a caller store a file whose type or destination the application does not properly constrain.

If an uploaded file lands anywhere the server will execute, the flaw becomes remote code execution and the site should be treated as fully compromised. For WPForms Pro the fix is 2.0.0: builds <= 1.10.1.1 are affected, anything from 2.0.0 onward is not.

Remediation

Update to version 2.0.0, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: WPForms Pro 2.0.0 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Login Security

External References

https://www.cve.org/CVERecord?id=CVE-2026-10818https://www.wordfence.com/threat-intel/vulnerabilities/id/b267f163-966a-43f7-8a7c-67d34c2c7e9dhttps://nvd.nist.gov/vuln/detail/CVE-2026-10818

Related records

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