CVE-2019-25746: SQL Injection in WordPress Sliced Invoices 3.8.2

Technical summary

CVE-2019-25746 is an authenticated SQL injection vulnerability (CWE-89) in Sliced Invoices 3.8.2. The vulnerability exists in the admin.php endpoint's duplicate_quote_invoice action handler, where the 'post' parameter is insufficiently sanitized before being incorporated into database queries. An authenticated attacker can inject arbitrary SQL syntax through this parameter to manipulate query logic, potentially extracting sensitive data from the WordPress database or modifying existing records. The CVSS 3.1 score of 7.1 (HIGH) reflects high confidentiality impact with limited integrity impact, requiring prior authentication.

Business impact

Organizations relying on Sliced Invoices for billing workflows face exposure of invoice data, customer payment information, and other sensitive database records. A compromised or malicious user with WordPress editor or higher privileges could extract client details, modify invoice amounts or payment statuses, or pivot to other database tables depending on database permissions. This threatens financial data integrity, regulatory compliance (PCI DSS, GDPR), and customer trust. The blast radius expands in environments with shared WordPress admin accounts or weak credential hygiene.

Affected systems

The vulnerability specifically affects Sliced Invoices plugin version 3.8.2 running on WordPress instances. Organizations should verify whether they are running this exact version or versions close to the 3.8.2 timeframe. Verify patch status against the vendor advisory to confirm which versions contain the fix. The risk is scoped to WordPress installations with Sliced Invoices active; non-WordPress deployments are unaffected.

Exploitability

Exploitation requires valid WordPress authentication credentials at a minimum (editor role or higher based on typical plugin admin restrictions). No user interaction or complex network conditions are necessary once the attacker has valid credentials. This makes the vulnerability moderately exploitable in organizations where WordPress accounts are not closely managed, shared across users, or where credentials have been compromised through phishing or weak password practices. The attack surface expands significantly in multi-tenant or agency WordPress environments.

Remediation

Update Sliced Invoices to a patched version released after 3.8.2. Verify the specific fixed version through the plugin vendor's official advisory or WordPress plugin repository. Additionally, enforce strong access controls: limit WordPress admin and editor roles to necessary personnel, enforce strong password policies, enable two-factor authentication (via plugins like Wordfence or WP 2FA), and monitor admin.php access logs for suspicious duplicate_quote_invoice requests. Consider restricting admin.php access by IP if feasible for your architecture.

Patch guidance

Check the WordPress plugin repository or the Sliced Invoices vendor website for the latest available version. Update the plugin through the WordPress admin dashboard (Plugins > Updates) once a patch is confirmed available. Test the update in a staging environment first to ensure compatibility with other plugins and your WordPress version. After patching, verify in the plugin settings that the version has incremented beyond 3.8.2. If no patch is available from the vendor, consider alternative invoice management plugins until a fix is released.

Detection guidance

Monitor for POST requests to admin.php with action=duplicate_quote_invoice parameters containing unusual SQL syntax (keywords like UNION, SELECT, OR, --, /*). Log and review database queries executed by the WordPress user running the plugin for anomalous patterns. Use a WordPress security plugin with intrusion detection (e.g., Wordfence, Sucuri) to alert on SQL injection attempts. Check database access logs for unexpected queries or data extraction patterns. Audit the WordPress user_meta and postmeta tables for unauthorized modifications to invoice data in the post_modified timestamps around suspicious access times.

Why prioritize this

This vulnerability ranks as HIGH priority for any organization running Sliced Invoices 3.8.2. The combination of authenticated access (limiting blast radius but not eliminating risk in multi-user environments), direct access to sensitive financial data, and the prevalence of WordPress compromise tactics make this a credible threat. Organizations should patch within 30 days, sooner if they have multiple WordPress users or if credential compromise is suspected.

Risk score, explained

The CVSS 3.1 score of 7.1 reflects high confidentiality impact (sensitive database data can be read), limited integrity impact (data can be modified but not in all contexts), and no availability impact. The requirement for prior authentication (PR:L) prevents a score in the Critical range but still places this in HIGH severity. The network-accessible nature (AV:N) and low attack complexity (AC:L) make it a practical threat once credentials are obtained.

Frequently asked questions