CVE-2026-9189 (GCVE-0-2026-9189)
Vulnerability from cvelistv5 – Published: 2026-05-29 08:28 – Updated: 2026-05-29 10:04
VLAI
Title
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)
Summary
The Contact Form 7 – 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.
Severity
5.3 (Medium)
CWE
- CWE-345 - Insufficient Verification of Data Authenticity
Assigner
References
8 references
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| scottpaterson | Contact Form 7 – PayPal & Stripe Add-on |
Affected:
0 , ≤ 2.4.9
(semver)
|
Credits
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-9189",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-29T10:00:42.885449Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-05-29T10:04:53.551Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Contact Form 7 \u2013 PayPal \u0026 Stripe Add-on",
"vendor": "scottpaterson",
"versions": [
{
"lessThanOrEqual": "2.4.9",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Muni Nitish Kumar Yaddala"
}
],
"descriptions": [
{
"lang": "en",
"value": "The Contact Form 7 \u2013 PayPal \u0026 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\u0027s `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."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
"version": "3.1"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-345",
"description": "CWE-345 Insufficient Verification of Data Authenticity",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-05-29T08:28:24.446Z",
"orgId": "b15e7b5b-3da4-40ae-a43c-f7aa60e62599",
"shortName": "Wordfence"
},
"references": [
{
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/5e274781-1c20-4224-bc10-26dadb9b1e07?source=cve"
},
{
"url": "https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/paypal_handler.php#L106"
},
{
"url": "https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/paypal_handler.php#L75"
},
{
"url": "https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/functions.php#L31"
},
{
"url": "https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/paypal_handler.php#L106"
},
{
"url": "https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/paypal_handler.php#L75"
},
{
"url": "https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/functions.php#L31"
},
{
"url": "https://plugins.trac.wordpress.org/changeset/3551197/contact-form-7-paypal-add-on"
}
],
"timeline": [
{
"lang": "en",
"time": "2026-05-21T15:22:09.000Z",
"value": "Vendor Notified"
},
{
"lang": "en",
"time": "2026-05-28T19:54:04.000Z",
"value": "Disclosed"
}
],
"title": "Contact Form 7 \u2013 PayPal \u0026 Stripe Add-on \u003c= 2.4.9 - Unauthenticated Payment Bypass via Insufficient Verification of Data Authenticity via PayPal IPN Handler (\u0027invoice\u0027/\u0027mc_gross\u0027 Verification)"
}
},
"cveMetadata": {
"assignerOrgId": "b15e7b5b-3da4-40ae-a43c-f7aa60e62599",
"assignerShortName": "Wordfence",
"cveId": "CVE-2026-9189",
"datePublished": "2026-05-29T08:28:24.446Z",
"dateReserved": "2026-05-21T15:06:53.761Z",
"dateUpdated": "2026-05-29T10:04:53.551Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-9189",
"date": "2026-05-29",
"epss": "0.00033",
"percentile": "0.10282"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-9189\",\"sourceIdentifier\":\"security@wordfence.com\",\"published\":\"2026-05-29T09:16:18.560\",\"lastModified\":\"2026-05-29T13:09:05.450\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"The Contact Form 7 \u2013 PayPal \u0026 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\u0027s `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.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security@wordfence.com\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N\",\"baseScore\":5.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":3.9,\"impactScore\":1.4}]},\"weaknesses\":[{\"source\":\"security@wordfence.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-345\"}]}],\"references\":[{\"url\":\"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/functions.php#L31\",\"source\":\"security@wordfence.com\"},{\"url\":\"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/paypal_handler.php#L106\",\"source\":\"security@wordfence.com\"},{\"url\":\"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/paypal_handler.php#L75\",\"source\":\"security@wordfence.com\"},{\"url\":\"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/functions.php#L31\",\"source\":\"security@wordfence.com\"},{\"url\":\"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/paypal_handler.php#L106\",\"source\":\"security@wordfence.com\"},{\"url\":\"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/paypal_handler.php#L75\",\"source\":\"security@wordfence.com\"},{\"url\":\"https://plugins.trac.wordpress.org/changeset/3551197/contact-form-7-paypal-add-on\",\"source\":\"security@wordfence.com\"},{\"url\":\"https://www.wordfence.com/threat-intel/vulnerabilities/id/5e274781-1c20-4224-bc10-26dadb9b1e07?source=cve\",\"source\":\"security@wordfence.com\"}]}}",
"vulnrichment": {
"containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-9189\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-05-29T10:00:42.885449Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-05-29T10:04:47.955Z\"}}], \"cna\": {\"title\": \"Contact Form 7 \\u2013 PayPal \u0026 Stripe Add-on \u003c= 2.4.9 - Unauthenticated Payment Bypass via Insufficient Verification of Data Authenticity via PayPal IPN Handler (\u0027invoice\u0027/\u0027mc_gross\u0027 Verification)\", \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Muni Nitish Kumar Yaddala\"}], \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 5.3, \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N\"}}], \"affected\": [{\"vendor\": \"scottpaterson\", \"product\": \"Contact Form 7 \\u2013 PayPal \u0026 Stripe Add-on\", \"versions\": [{\"status\": \"affected\", \"version\": \"0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"2.4.9\"}], \"defaultStatus\": \"unaffected\"}], \"timeline\": [{\"lang\": \"en\", \"time\": \"2026-05-21T15:22:09.000Z\", \"value\": \"Vendor Notified\"}, {\"lang\": \"en\", \"time\": \"2026-05-28T19:54:04.000Z\", \"value\": \"Disclosed\"}], \"references\": [{\"url\": \"https://www.wordfence.com/threat-intel/vulnerabilities/id/5e274781-1c20-4224-bc10-26dadb9b1e07?source=cve\"}, {\"url\": \"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/paypal_handler.php#L106\"}, {\"url\": \"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/paypal_handler.php#L75\"}, {\"url\": \"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.8/includes/payments/functions.php#L31\"}, {\"url\": \"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/paypal_handler.php#L106\"}, {\"url\": \"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/paypal_handler.php#L75\"}, {\"url\": \"https://plugins.trac.wordpress.org/browser/contact-form-7-paypal-add-on/tags/2.4.6/includes/payments/functions.php#L31\"}, {\"url\": \"https://plugins.trac.wordpress.org/changeset/3551197/contact-form-7-paypal-add-on\"}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"The Contact Form 7 \\u2013 PayPal \u0026 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\u0027s `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.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-345\", \"description\": \"CWE-345 Insufficient Verification of Data Authenticity\"}]}], \"providerMetadata\": {\"orgId\": \"b15e7b5b-3da4-40ae-a43c-f7aa60e62599\", \"shortName\": \"Wordfence\", \"dateUpdated\": \"2026-05-29T08:28:24.446Z\"}}}",
"cveMetadata": "{\"cveId\": \"CVE-2026-9189\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-05-29T10:04:53.551Z\", \"dateReserved\": \"2026-05-21T15:06:53.761Z\", \"assignerOrgId\": \"b15e7b5b-3da4-40ae-a43c-f7aa60e62599\", \"datePublished\": \"2026-05-29T08:28:24.446Z\", \"assignerShortName\": \"Wordfence\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
Loading…