CVE-2026-9857 in Invoice123 Plugin
Summary
by MITRE • 07/10/2026
The Invoice123 plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 1.7.0. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with subscriber-level access and above, to overwrite the plugin's API key stored in wp_options, modify invoice plugin settings, and alter WooCommerce tax rate data in the wp_woocommerce_tax_rates table.
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Analysis
by VulDB Data Team • 07/10/2026
The Invoice123 WordPress plugin presents a critical authorization bypass vulnerability that compromises the security of WordPress installations using versions up to and including 1.7.0. This flaw stems from insufficient user permission validation within the plugin's code implementation, creating a pathway for malicious actors who possess subscriber-level privileges or higher to execute unauthorized administrative actions. The vulnerability exists because the plugin fails to properly authenticate user roles before permitting sensitive operations that should be restricted to administrators or users with elevated privileges.
The technical nature of this authorization bypass allows attackers to manipulate core WordPress database elements through the wp_options table where the plugin stores its API key configuration. This manipulation capability extends beyond simple data modification to include complete overwrite of critical authentication credentials that the plugin relies upon for proper operation. Additionally, the vulnerability permits unauthorized changes to invoice plugin settings that govern how invoices are generated and processed, potentially enabling attackers to redirect payment processing or alter billing information. The compromise also extends to the wp_woocommerce_tax_rates table where WooCommerce tax configurations reside, allowing malicious actors to modify tax rate data that directly impacts financial calculations and compliance reporting.
The operational impact of this vulnerability is significant for WordPress administrators who rely on the Invoice123 plugin for business-critical functions. Attackers with subscriber-level access can effectively gain administrative control over invoice processing functionality without triggering standard security alerts or requiring additional privilege escalation techniques. This authorization bypass creates a persistent backdoor that remains undetected by typical security monitoring systems since the actions occur within legitimate plugin interfaces. The vulnerability affects the integrity of financial data, potentially leading to revenue loss, compliance violations, and disruption of business operations through unauthorized changes to tax configurations and invoice processing parameters.
Security mitigation strategies should prioritize immediate plugin updates to versions that address the authorization bypass flaw, as this represents the most direct solution to the identified vulnerability. Organizations should implement role-based access controls that limit user privileges to only those necessary for specific functions, reducing the potential impact of compromised accounts. Database query monitoring and auditing should be enabled to detect unauthorized modifications to wp_options and wp_woocommerce_tax_rates tables, with alerts configured for any changes to critical plugin configuration data. Network segmentation and application firewalls can help prevent unauthorized access to administrative interfaces while implementing multi-factor authentication for all administrative accounts. The vulnerability aligns with CWE-285 authorization bypass weaknesses and represents a technique commonly associated with privilege escalation attacks in the MITRE ATT&CK framework, specifically under the credential access and defense evasion categories where attackers seek to maintain persistent access through legitimate administrative functions.
This vulnerability demonstrates the importance of proper input validation and authentication checks within WordPress plugins, particularly those handling sensitive financial data. The flaw represents a common security oversight where developers assume that user roles are properly enforced without implementing explicit verification mechanisms for privileged operations. Organizations should conduct regular security assessments of all installed plugins to identify similar authorization bypass vulnerabilities that could compromise their WordPress environments and potentially lead to more extensive system breaches through lateral movement techniques.