Attack Chain

1. The attacker sends a crafted HTTP POST request to the /payment/api/editable/update endpoint.
2. The request contains malicious PHP code within the POST parameters, designed for remote code execution.
3. The vulnerable endpoint uses file_put_contents() to write the attacker-supplied PHP code directly into an existing PHP file, overwriting its original content.
4. The overwritten PHP file is located within the payment processing directory.
5. During normal payment processing, the application uses require() to include and execute the modified PHP file.
6. The attacker's malicious PHP code is executed on the server with the permissions of the web server user.
7. The attacker gains control of the server, enabling activities like installing web shells.

Impact

Successful exploitation of CVE-2026-31843 allows unauthenticated attackers to achieve remote code execution on the affected server. This could lead to complete compromise of the system, potentially affecting sensitive data such as customer payment information, API keys, and other confidential data stored within the Laravel application. The impact is particularly severe for e-commerce platforms and any application processing financial transactions using the vulnerable package.

Recommendation

• Upgrade the goodoneuz/pay-uz Laravel package to a patched version greater than 2.2.24 to remediate CVE-2026-31843.
• Monitor web server logs for suspicious POST requests to the /payment/api/editable/update endpoint as described in the attack chain.
• Deploy the Sigma rule Detect Pay-UZ Laravel RCE Attempt to identify exploitation attempts via HTTP requests to the vulnerable endpoint.
• Enable web server logging to capture HTTP POST request data for effective detection and investigation.