CVE-2026-57677: Novalnet Payment Gateway Auth Bypass Flaw

CVE-2026-57677 Overview

CVE-2026-57677 is an unauthenticated PHP Object Injection vulnerability in the Novalnet Payment Gateway for WooCommerce plugin, affecting versions up to and including 12.10.3. The flaw stems from insecure deserialization of untrusted input [CWE-502], allowing remote attackers to inject arbitrary PHP objects without authentication. When combined with a suitable gadget chain in the WordPress environment, exploitation can lead to remote code execution, sensitive data disclosure, or complete site compromise. WooCommerce merchants using Novalnet for payment processing are exposed to full site takeover through network-accessible attack paths.

Critical Impact
Unauthenticated attackers can trigger PHP object injection over the network, potentially leading to remote code execution and full compromise of WooCommerce storefronts running vulnerable Novalnet Payment Gateway versions.

Affected Products

Novalnet Payment Gateway for WooCommerce plugin versions <= 12.10.3
WordPress installations running the woocommerce-novalnet-gateway plugin
WooCommerce e-commerce sites integrating Novalnet payment processing

Discovery Timeline

2026-07-02 - CVE-2026-57677 published to NVD
2026-07-02 - Last updated in NVD database

Technical Details for CVE-2026-57677

Vulnerability Analysis

The vulnerability is classified as insecure deserialization [CWE-502]. The Novalnet Payment Gateway for WooCommerce plugin passes attacker-controlled input into a PHP deserialization routine without validation. PHP's unserialize() function reconstructs objects from serialized strings and invokes magic methods such as __wakeup() and __destruct() during processing. Attackers can craft serialized payloads that instantiate arbitrary classes present in the WordPress or WooCommerce runtime.

When a suitable gadget chain exists in the loaded codebase, this object instantiation escalates to arbitrary file writes, SQL injection, or remote code execution. The attack requires no authentication and no user interaction. Exploitation occurs over the network against publicly reachable WordPress endpoints exposed by the plugin. See the Patchstack Vulnerability Report for further technical context.

Root Cause

The plugin deserializes user-supplied data through unserialize() without sanitizing or validating the input. This allows attackers to pass crafted serialized PHP objects into application logic. Combined with autoloaded WordPress and WooCommerce classes, the deserialization path becomes an object injection primitive.

Attack Vector

Attackers deliver a malicious serialized payload to a vulnerable endpoint exposed by the Novalnet plugin. The payload is deserialized server-side, instantiating attacker-chosen classes. Magic methods executed during deserialization drive the gadget chain toward code execution or state manipulation. No credentials or user interaction are required. Refer to the Patchstack Vulnerability Report for advisory details.

Detection Methods for CVE-2026-57677

Indicators of Compromise

Unexpected serialized PHP data patterns such as O:, a:, or s: appearing in HTTP POST bodies or query parameters directed at Novalnet plugin endpoints.
Creation or modification of PHP files in wp-content/uploads/ or plugin directories after requests reach Novalnet handlers.
Outbound network connections initiated by the php-fpm or web server process shortly after inbound requests to WooCommerce checkout or callback URLs.
New administrator accounts or unexpected WordPress option changes in the wp_options table.

Detection Strategies

Inspect web server logs for POST requests to Novalnet plugin endpoints containing serialized object markers.
Deploy web application firewall rules that flag or block serialized PHP payloads in request bodies to WordPress sites.
Monitor file integrity across the WordPress installation and alert on unauthorized changes to PHP files.

Monitoring Recommendations

Enable verbose access logging on WooCommerce endpoints and forward logs to a centralized analytics platform.
Correlate anomalous process execution from the web server user against inbound HTTP requests to detect deserialization-driven code execution.
Track plugin version inventory across WordPress fleets and alert on hosts still running woocommerce-novalnet-gateway <= 12.10.3.

How to Mitigate CVE-2026-57677

Immediate Actions Required

Update the Novalnet Payment Gateway for WooCommerce plugin to a version newer than 12.10.3 as soon as a patched release is available from the vendor.
Audit WordPress installations for the presence of woocommerce-novalnet-gateway and prioritize patching internet-facing storefronts.
Review web server and WordPress logs for prior exploitation attempts targeting Novalnet plugin endpoints.
Rotate WordPress administrator credentials, API keys, and payment gateway secrets if compromise is suspected.

Patch Information

Consult the Patchstack Vulnerability Report for the latest fixed version guidance. Apply the vendor-supplied update through the WordPress plugin manager or by replacing the plugin files with the patched release.

Workarounds

Deactivate the Novalnet Payment Gateway for WooCommerce plugin until a patched version can be installed.
Restrict access to WooCommerce checkout and payment callback URLs using IP allowlists where operationally feasible.
Deploy a WAF ruleset that blocks serialized PHP object patterns in request parameters routed to WordPress.

bash

# Example WAF rule (ModSecurity) blocking serialized PHP objects in requests
SecRule REQUEST_BODY|ARGS "@rx (?:^|[;&])(?:O|a|s|i|b|d):[0-9]+:" \
    "id:1057677,phase:2,deny,status:403,\
    msg:'Potential PHP object injection payload - CVE-2026-57677'"