CVE-2026-39666
DOM-Based XSS in Hello Bar Popup Builder
Publication date: 2026-04-08
Last updated on: 2026-04-08
Assigner: Patchstack
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| hellobar | popup_builder | From 1.0.0 (inc) to 1.5.1 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-79 | The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. |
Attack-Flow Graph
AI Powered Q&A
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.
Can you explain this vulnerability to me?
CVE-2026-39666 is a Cross Site Scripting (XSS) vulnerability in the WordPress Hello Bar Popup Builder Plugin versions up to and including 1.5.1.
This vulnerability allows attackers to inject malicious scripts—such as redirects, advertisements, or other HTML payloads—into websites using the plugin. These scripts execute when visitors access the affected site.
The issue is classified under OWASP Top 10 A3: Injection and has a CVSS severity score of 6.5, indicating a moderate risk level.
Exploitation requires a user with at least Contributor or Developer privileges to perform an action like clicking a malicious link, visiting a crafted page, or submitting a form, meaning user interaction is necessary.
How can this vulnerability impact me? :
This vulnerability can impact you by allowing attackers to inject and execute malicious scripts on your website, which can lead to:
- Redirecting visitors to malicious or unwanted websites.
- Displaying unauthorized advertisements or unwanted content.
- Potentially compromising user data or session information through script execution.
Although it is used in mass-exploit campaigns targeting many websites, it is considered a moderate risk and currently has no reported impactful threat.
What immediate steps should I take to mitigate this vulnerability?
The recommended immediate mitigation is to update the Hello Bar Popup Builder plugin once an official patch is released.
Until a patch is available, seek assistance from your hosting provider or web developers to implement temporary protections.