WordPress GetPaid Plugin Stored XSS via Unvalidated Parameters

The Payment forms, Buy now buttons, and Invoicing System | GetPaid plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'mmdwqzpoxadd' parameter in all versions up to, and including, 2.8.61 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The required nonce (getpaid_form_nonce) is publicly emitted to all visitors via wp_localize_script as WPInv.formNonce, meaning no authentication or prior nonce leak is needed; the stored payload fires when an administrator views the affected invoice's Payment Form Details metabox.

Casky was already ahead

This CVE exploits attack patterns that Casky's 323matched 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

The GetPaid WordPress plugin contains a Stored Cross-Site Scripting (XSS) vulnerability in versions up to 2.8.61, allowing unauthenticated attackers to inject malicious scripts through the 'mmdwqzpoxadd' parameter in payment forms, buy buttons, and invoicing components. Because the nonce (getpaid_form_nonce) is publicly exposed to all visitors, attackers can bypass CSRF protections and inject payloads without authentication. Once stored, these scripts execute in the browsers of any user accessing the compromised page, making this a high-severity threat (CVSS 7.2) for e-commerce sites and organizations relying on GetPaid for payment processing. The vulnerability affects anyone running the plugin, from small businesses to enterprises processing customer transactions.

Casky's 323 mapped security skills detect this attack pattern by correlating CWE-79 (Improper Neutralization of Input During Web Page Generation) with MITRE ATT&CK techniques TA0001 (Reconnaissance) and TA0043 (Reconnaissance for Defense Evasion). Practitioners using Casky would identify findings showing: (1) insufficient input sanitization on form parameters, (2) missing output encoding in rendered HTML contexts, (3) publicly accessible CSRF tokens enabling unauthenticated exploitation, and (4) stored payload persistence across sessions. Claude's extended reasoning capability traces the attack chain from parameter injection through DOM manipulation to payload execution, highlighting how attackers perform initial reconnaissance of GetPaid deployments, craft nonce-less exploitation payloads, and establish persistent backdoor access for credential harvesting or malware distribution.

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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 →

323 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-111110.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0043

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