CVE-2026-39666
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedImproper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in telepathy Hello Bar Popup Builder hellobar allows DOM-Based XSS.This issue affects Hello Bar Popup Builder: from n/a through <= 1.5.1.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceDOM-Based XSS vulnerability in the Hello Bar Popup Builder plugin allows attackers to inject malicious JavaScript through unsanitized user input that gets directly executed in the browser's DOM. The vulnerability stems from improper neutralization of input during web page generation.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify Hello Bar Popup Builder plugin is installedAccess your website's plugin directory or WordPress admin panel and confirm the Hello Bar Popup Builder plugin is present and activeAffected if The plugin is installed and active in the environment
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Identify the installed plugin versionCheck the plugin header in the main plugin file (typically in wp-content/plugins/hello-bar-popup-builder/ or similar path) for the Version field, or view the plugin details in the WordPress plugins admin pageAffected if The installed version falls within any affected version range for this CVE (compare your version to the officially listed affected versions)
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Confirm popup builder functionality is in useNavigate to the plugin settings or popup builder interface and determine if any popups, bars, or notification boxes have been created using user-supplied input in the message content, links, or display triggersAffected if Active popups exist that accept and display user input in the DOM without sanitization
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Inspect DOM for unsanitized input reflectionLoad a page containing a Hello Bar popup in a browser, right-click and select Inspect Element, then examine the HTML source to see if popup content appears as raw text within HTML tags (e.g., inside <div>, <span>, or <a> attributes) without proper encodingAffected if Popup content is inserted directly into the DOM without HTML entity encoding or sanitization functions being applied
The environment is affected if the Hello Bar Popup Builder plugin is installed, the installed version is within the affected range, and the plugin is actively displaying popups with user-supplied input that is inserted into the DOM without sanitization.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpdate to the latest version of Hello Bar Popup Builder when a patch is released, or implement output encoding and use safe DOM methods (textContent/innerText instead of innerHTML) for any user-supplied data.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-39666 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-39666 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data