Contact Form 7 – PayPal & Stripe Add-on <= 2.4.9 - Unauthenticated Payment Bypass via Insufficient Verification of Data Authenticity via PayPal IPN Handler ('invoice'/'mc_gross' Verification)_CVE-2026-9189

{
    "lastseen": "",
    "description": "The Contact Form 7 \u2013 PayPal & Stripe Add-on plugin for WordPress is vulnerable to Payment Bypass via Insufficient Verification of Data Authenticity in all versions up to, and including, 2.4.9. Although `cf7pp_paypal_ipn_handler()` correctly validates IPN authenticity by posting back to PayPal with `cmd=_notify-validate`, it fails to compare the IPN payload's `mc_gross` (payment amount), `mc_currency`, or `receiver_email` fields against the corresponding stored order values before passing the attacker-controlled `invoice` field directly to `cf7pp_complete_payment()`, which marks the order completed after only an integer cast with no amount verification. This makes it possible for unauthenticated attackers to mark arbitrary high-value pending orders as fully paid by making a minimal real PayPal payment and crafting an IPN whose `invoice` parameter references the targeted order, effectively completing purchases without tendering the required payment amount.",
    "published": "2026-05-29T08:28:24.446Z",
    "modified": "2026-05-29T08:28:24.446Z",
    "type": "cve",
    "title": "Contact Form 7 \u2013 PayPal & Stripe Add-on <= 2.4.9 - Unauthenticated Payment Bypass via Insufficient Verification of Data Authenticity via PayPal IPN Handler ('invoice'/'mc_gross' Verification)",
    "source": "Wordfence",
    "references": "https://www.wordfence.com/threat-intel/vulnerabilities/id/5e274781-1c20-4224-bc10-26dadb9b1e07?source=cve\nhttps://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/paypal_handler.php#L106\nhttps://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/paypal_handler.php#L75\nhttps://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/functions.php#L31\nhttps://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/paypal_handler.php#L106\nhttps://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/paypal_handler.php#L75\nhttps://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/functions.php#L31\nhttps://plugins.trac.wordpress.org/changeset/3551197/contact-form-7-paypal-add-on",
    "id": "CVE-2026-9189",
    "bulletinFamily": "",
    "cwe": [
        "CWE-345"
    ],
    "cvelist": null,
    "sourceData": "scottpaterson Contact Form 7 \u2013 PayPal & Stripe Add-on 0",
    "sourceHref": "",
    "cvss": {
        "score": 5.3,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Contact Form 7 \u2013 PayPal & Stripe Add-on",
    "version": "0",
    "vendor": "scottpaterson",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}