CVE-2025-39381: KiotViet Sync CSRF Vulnerability

CVE-2025-39381 Overview

CVE-2025-39381 is a Cross-Site Request Forgery (CSRF) vulnerability in the KiotViet Sync WordPress plugin that enables attackers to inject persistent malicious scripts (Stored XSS) into affected websites. This chained attack allows unauthenticated attackers to trick authenticated administrators into executing unauthorized actions, ultimately leading to the injection of malicious JavaScript that persists in the WordPress database and executes in the browsers of subsequent visitors.

Critical Impact

This CSRF-to-Stored XSS vulnerability chain allows attackers to hijack administrator sessions, steal sensitive credentials, deface websites, or redirect users to malicious destinations without requiring direct authentication.

Affected Products

• KiotViet Sync WordPress plugin versions from n/a through 1.8.4
• WordPress installations running the vulnerable KiotViet Sync plugin
• E-commerce sites utilizing KiotViet inventory synchronization

Discovery Timeline

• 2025-04-24 - CVE CVE-2025-39381 published to NVD
• 2026-04-28 - Last updated in NVD database

Technical Details for CVE-2025-39381

Vulnerability Analysis

This vulnerability represents a compound attack chain combining Cross-Site Request Forgery (CWE-352) with Stored Cross-Site Scripting. The KiotViet Sync plugin fails to implement proper CSRF token validation on critical administrative endpoints, allowing attackers to craft malicious requests that, when triggered by an authenticated administrator, write attacker-controlled content directly into the WordPress database. Because the injected payload is stored persistently, it executes every time a user views the affected page or administrative interface, significantly amplifying the attack's impact.

The attack requires user interaction—specifically, an authenticated administrator must visit a malicious page or click a crafted link. However, once triggered, the stored XSS payload operates autonomously, affecting all subsequent visitors without further attacker involvement.

Root Cause

The root cause of this vulnerability is the absence of CSRF token validation (nonce verification) on form submission handlers within the KiotViet Sync plugin. WordPress provides built-in functions such as wp_nonce_field() and wp_verify_nonce() specifically to prevent CSRF attacks, but the vulnerable versions of this plugin fail to implement these protections on sensitive endpoints. Additionally, the plugin does not properly sanitize or escape user-supplied input before storing it in the database, enabling the Stored XSS component of the attack chain.

Attack Vector

The attack is network-based and requires an authenticated WordPress administrator to be tricked into visiting an attacker-controlled page while logged into the target WordPress site. The attacker crafts a malicious HTML page containing an auto-submitting form that targets the vulnerable KiotViet Sync endpoint. When the administrator visits this page, their browser automatically submits the form with their valid session cookies, causing the malicious payload to be stored in the WordPress database.

A typical attack scenario involves the attacker embedding malicious JavaScript (such as session-stealing code or keyloggers) in the form payload. This approach relies on social engineering techniques—commonly delivered via phishing emails, forum posts, or embedded content on compromised websites—to lure the victim to the malicious page.

Detection Methods for CVE-2025-39381

Indicators of Compromise

• Unexpected JavaScript or HTML code in KiotViet Sync plugin settings or stored data fields
• HTTP POST requests to KiotViet Sync administrative endpoints originating from external referrers
• Newly created administrator accounts or modified user privileges without authorized changes
• Browser console errors or unexpected script executions on WordPress admin pages

Detection Strategies

• Monitor HTTP server logs for POST requests to KiotViet Sync endpoints with external or suspicious Referer headers
• Implement Content Security Policy (CSP) headers to detect and block unauthorized inline script execution
• Review WordPress database tables associated with KiotViet Sync for injected <script> tags or event handlers
• Deploy web application firewall (WAF) rules to detect CSRF attack patterns and XSS payloads

Monitoring Recommendations

• Enable WordPress audit logging to track changes to plugin settings and stored data
• Configure real-time alerting for modifications to critical plugin configuration values
• Perform regular integrity checks on stored plugin data to identify unauthorized modifications
• Monitor for outbound connections from the WordPress server to unknown external domains

How to Mitigate CVE-2025-39381

Immediate Actions Required

• Update the KiotViet Sync plugin to a patched version that addresses the CSRF and XSS vulnerabilities
• Review KiotViet Sync plugin settings and stored data for any evidence of injected malicious scripts
• Invalidate all active WordPress administrator sessions and require password resets
• Implement Web Application Firewall (WAF) rules to block suspicious requests targeting the plugin

Patch Information

A security update addressing CVE-2025-39381 should be obtained from the official WordPress plugin repository or directly from the vendor. Administrators should verify they are running a version newer than 1.8.4. For detailed vulnerability information and remediation guidance, refer to the Patchstack Vulnerability Report.

Workarounds

• Temporarily disable the KiotViet Sync plugin until a patched version is available
• Restrict access to WordPress administrative interfaces using IP allowlisting
• Implement browser-based CSRF protection extensions for administrators during vulnerable periods
• Enable two-factor authentication for all WordPress administrator accounts to reduce session hijacking risk

# Configuration example - Disable plugin via WP-CLI
wp plugin deactivate kiotvietsync

# Verify plugin status
wp plugin status kiotvietsync

# Check for stored XSS in plugin options (search for script tags)
wp db query "SELECT * FROM wp_options WHERE option_name LIKE '%kiotviet%' AND option_value LIKE '%<script%';"