Unauthenticated Payment Intent Amount Manipulation

The Stripe Payment Forms by WP Full Pay WordPress plugin before 8.5.2 does not verify that the caller owns the Stripe payment intent referenced by two unauthenticated payment-form AJAX actions, allowing an unauthenticated visitor — using a nonce that is embedded in every public page containing a payment form — to change the amount of a payment intent that the Stripe Payment Forms by WP Full Pay WordPress plugin before 8.5.2 then updates server-side through the Stripe API with the store's secret key. An ownership check added in 8.5.0 was applied to only one payment-intent handler, leaving the pricing-recalculation and payment-intent-update actions unprotected against amount manipulation.

Casky was already ahead

This CVE exploits attack patterns that Casky's 283matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

This vulnerability affects the Stripe Payment Forms by WP Full Pay WordPress plugin versions before 8.5.2, allowing unauthenticated attackers to manipulate payment amounts through unverified AJAX actions. The plugin fails to validate that the caller owns the Stripe payment intent being modified, enabling an attacker with access to a nonce (embedded in public pages) to alter payment amounts before they're processed server-side via the Stripe API. This impacts any WordPress site using the vulnerable plugin, potentially leading to unauthorized financial transactions, revenue loss, and customer payment fraud. The attack requires minimal effort—only knowledge of a payment intent identifier and a publicly available nonce—making it a critical authorization bypass issue.

Casky's 283 mapped skills detect the attack patterns underlying this CVE by analyzing MITRE ATT&CK techniques TA0004 (Privilege Escalation) and TA0006 (Credential Access). Practitioners using Claude AI extended reasoning will identify suspicious patterns such as: unauthenticated requests modifying financial transaction parameters, nonce reuse across multiple payment intents, anomalous amount changes in payment processing workflows, and API calls lacking proper ownership verification. The skills framework flags CWE-862 (Missing Authorization) violations where AJAX handlers process payment modifications without validating caller identity or intent ownership. Security teams will surface findings showing unauthorized payment intent manipulation attempts, unusual nonce patterns from non-owner IP addresses, and mismatches between user sessions and modified payment amounts—enabling rapid detection before financial damage occurs.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

283 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-16734.

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

Access with Stolen Session Cookie

cryptography · low

Run

MITRE ATT&CK Techniques

TA0004 TA0006

Investigate the attack patterns behind CVE-2026-16734

Casky has 283 skills that investigate the attack patterns behind CVE-2026-16734. Run one and get CVSS-scored findings in 3 minutes.

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