External risk intelligence

Webenvo Subscriber Arbitrary File Upload Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.9)

CVE-2026-39589

A critical arbitrary file upload vulnerability exists in the Webenvo theme, potentially allowing unauthorized access and compromise of websites. An attacker could leverage this to upload malicious files, impacting system integrity and availability. It is important to verify if your organization uses this theme and asse

Unrestricted File Upload

Halo Surface Signal

Likely · external exposure

4Halo Surface Signal

The vulnerability affects a WordPress theme, which are commonly used to build public-facing websites. Because the product is designed to render content and handle uploads over the internet as part of standard web server operations, it is likely to be exposed to public network traffic.

Horizon Alert

Summary of the vulnerability and why it matters

This CVE involves a critical security flaw in the Webenvo theme, allowing unauthorized file uploads. This could potentially lead to unauthorized access or control over websites using this theme. The main concern is to confirm if your organization uses this specific theme and assess any potential exposure.

  • Allows unauthorized file uploads.
  • Critical flaw in widely used web technology.
  • Verify use and assess exposure.

Attack Path

How an attacker could exploit the issue

An attacker could gain unauthorized access to upload malicious files by exploiting a weakness in the Webenvo theme. This allows them to potentially compromise the website and its users.

  • Requires low privileges.
  • Uploading a crafted file.
  • Full website compromise.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an authenticated user to upload arbitrary files when the system is configured to use the Webenvo theme. This could impact the integrity and availability of the affected system.

  • Arbitrary file uploads.
  • Authenticated user uploads files.
  • System integrity and availability.

Operational Fix

Recommended remediation, mitigation, and detection steps

This arbitrary file upload vulnerability in Webenvo affects web applications, likely making platform or infrastructure teams responsible for initial assessment and remediation. The first practical step is to identify all instances of Webenvo, determine their exposure and business criticality, and then confirm the accountable owner to plan a risk-based remediation strategy.

  • Platform/Infrastructure teams own remediation.
  • Verify Webenvo instances and exposure.
  • Plan risk-based remediation actions.

Supplementary metadata

CVSS vector

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

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Frequently asked questions

What is the Webenvo theme?

Webenvo is a WordPress theme used to determine the visual design and layout of a website. Themes in WordPress act as a framework for site appearance, often including features that handle user-submitted content or interactive elements directly on public-facing pages.

What does CWE-434 mean for CVE-2026-39589?

This CVE is categorized as CWE-434, which refers to Unrestricted Upload of File with Dangerous Type. In simple terms, the software does not properly check the types of files being uploaded. This allows an attacker to bypass security rules and send malicious files to the server, which could then be executed to compromise the system.

How can an attacker trigger this vulnerability?

An attacker needs an account with subscriber-level privileges to interact with the theme's upload functionality. The vulnerability is not triggered by anonymous visitors; it requires a logged-in user to send a specially crafted file that the system fails to validate.

Is my website at risk from CVE-2026-39589?

According to Halo Surface Signal, this vulnerability is likely to be exposed to public network traffic. Because the Webenvo theme is used on WordPress sites that handle uploads over the internet, it is inherently accessible to attackers on the network, making it a higher priority if your site is internet-facing.

What should I do if I use the Webenvo theme?

Your first step is to perform an inventory of your environment to identify every instance where the Webenvo theme is active. Once identified, evaluate the business criticality of those sites and confirm the internal team responsible for the server infrastructure to coordinate risk-based updates or mitigation plans.

References

Sources and related resources

Primary sources: NVD, CVE.org.

NVDPublished