What happened (summary)

On 6 January 2026 a high‑priority SQL injection vulnerability (CVE-2025-13652) was disclosed in the WordPress plugin CBX Bookmark & Favorite. All plugin versions up to and including 2.0.4 are affected. The issue permits an authenticated user with Subscriber privileges to control the orderby parameter in a query in an unsafe way — enabling SQL injection.

The plugin author released version 2.0.5 containing the security fix. Site owners and administrators must prioritise updating to 2.0.5 immediately. If immediate update is not possible, apply virtual patches at the WAF level and follow the compensating controls described below.

Why this is serious

• Low privilege required: Only a Subscriber account is needed. Many sites allow registrations or have membership functionality, making the attack surface large.
• SQL injection severity: Unvalidated input placed into ORDER BY can be used to craft expressions or subqueries, enabling data exfiltration, tampering, or other impact.
• Exploitability: Creating or compromising a subscriber account is trivial in many environments, so remote exploitation is practical.
• CVSS: Rated CVSS 8.5 — treat as urgent.

Technical analysis — how the vulnerability works

The plugin constructs an SQL query using a user‑controlled orderby value and inserts it into the ORDER BY clause without proper validation or identifier whitelisting. ORDER BY accepts column names and expressions; if unvalidated input is interpolated directly, attackers can provide payloads (subqueries, operators, comments) to manipulate query execution and leak data via error messages, timing, or returned results.

Secure approaches that were not used here include:

• Whitelisting allowed order columns and mapping user inputs to those allowed values.
• Rejecting any input that contains SQL meta‑characters or keywords when used as identifiers or expressions.

Developer notes:

• Escaping string literals is not the same as securing identifiers — column names must be validated or mapped from a controlled list.
• Never accept arbitrary SQL fragments from users.

Exploitation impact and likely abuse scenarios

Impact depends on the database contents and how the vulnerable query is used. Potential outcomes:

• Data exfiltration: Attackers may read sensitive data (emails, hashed passwords, site options, custom data).
• Account compromise: Harvested emails or tokens can enable targeted phishing or account takeover.
• Data tampering: If writeable contexts are reachable, attackers could modify posts, settings, or create accounts.
• Persistence: Attackers may attempt to add administrator users or plant backdoors if they can combine this with other weaknesses.
• Lateral movement: Exfiltrated credentials or API keys could be reused against other systems.

Given the low privilege requirement, treat all installations of the plugin as at‑risk until patched or mitigated.

Immediate mitigation (do this now)

1. Update the plugin (recommended)

Update CBX Bookmark & Favorite to 2.0.5 or later on every site. This is the only complete fix. If you manage multiple sites, schedule an emergency maintenance window and roll out the update site‑wide.

2. If you cannot update immediately, apply these temporary measures

• Disable or harden user registration if it isn’t required. Prevent new Subscriber accounts until you patch.
• Audit existing Subscriber accounts: remove unknown accounts and enforce password resets for suspicious users.
• Apply virtual patches via your WAF or deploy strict request filtering to block malicious orderby payloads (see WAF rules section).
• Restrict access to plugin endpoints where possible (e.g., require valid nonces, limit AJAX endpoints by referrer or authentication checks).
• Tighten database privileges where feasible: ensure the WordPress DB user has only the minimum required privileges (avoid global or excessive privileges). Be careful when changing DB privileges on a live site.

3. Communicate

• Inform your team and stakeholders about the risk and update plan.
• Take a full backup (files + DB) before making changes.

WAF rules and virtual patches — practical guidance

If you cannot update immediately (staged rollouts, compatibility testing), a properly configured WAF can mitigate exploitation by blocking dangerous orderby payloads. Test in alert mode first to avoid blocking legitimate traffic.

Design principles:

• Prefer whitelisting over blacklisting: allow only safe patterns.
• Minimise false positives by mapping legitimate columns used by your site.
• Layer checks: parameter format, SQL keywords, encoded payload detection, and rate limits.

Example rule set (conceptual — convert to your WAF syntax)

1. Whitelist characters for orderby
   Allow only letters, numbers, underscores, dashes, commas and optional ASC/DESC. Regex concept:

   ^[A-Za-z0-9_,\s\-]+( (ASC|DESC))?(,[A-Za-z0-9_,\s\-]+( (ASC|DESC))?)*$

   Rationale: real column names rarely contain SQL keywords or comments.

2. Block SQL meta characters and keywords
   If orderby contains any of: ;, --, /*, */, union, select, insert, update, delete, drop, information_schema, block the request. Regex concept (case-insensitive):

   (?i)(;|--|\bunion\b|\bselect\b|\binformation_schema\b|/\*|\*/|\bdrop\b|\binsert\b)

3. Block comment and concatenation usage
   Block if request includes SQL comments (--, #, /*) or concatenation operators indicative of injection attempts.
4. Decode and inspect encoded payloads
   URL‑decode the parameter and re‑apply the same checks — attackers often encode characters to bypass naive filters.
5. Rate limit and throttle
   Apply rate limits for requests that set suspicious orderby values, especially from accounts with Subscriber role. Escalate to challenge (CAPTCHA) after repeated triggers.
6. Protect backend and AJAX endpoints
   Ensure AJAX endpoints require authentication and valid nonces. At the WAF level, require expected headers or block requests missing expected referers where appropriate.
7. Virtual patch
   IF request contains orderby AND NOT match whitelist pattern => block and log with high priority.

Notes: Some sites legitimately use multi‑column order strings; where possible maintain a site‑specific allowed column list and map user inputs to those columns at the application level.

Detecting exploitation — logs and IoCs

Search access logs, application logs and DB logs for signs of attempted or successful exploitation. Key indicators:

Web server / HTTP logs

• Requests including orderby= with suspicious characters: spaces followed by ( or ), semicolon ;, comment markers -- or /*, or SQL keywords like UNION, SELECT, INFORMATION_SCHEMA, OR 1=1.
• Search regex concept:

  orderby=.*(%20|;|--|/\*|\*/|\bOR\b|\bAND\b|\bUNION\b|\bSELECT\b)

• Look for encoded variants: %3B, %2D%2D, %2F%2A, %2A%2F.

Application and PHP logs

• Database errors containing SQL snippets or unexpected “unknown column” messages tied to plugin files.
• PHP warnings/errors in files that process sorting/query parameters.
• Spikes in requests to plugin endpoints.

Database indicators

• Unexpected SELECTs referencing tables outside normal scope (e.g., wp_users, wp_options).
• New/modified rows in core tables: unexpected admin users, changes to wp_options, or unexpected cron entries.
• Abnormal query patterns following a request that contained orderby.

General IoCs: accounts created near the time of suspicious activity, authentication from unusual IPs/geographies, and modifications to plugin/theme files.

Incident response checklist (if you suspect compromise)

1. Preserve evidence
   • Take a snapshot of site files and export a database dump for forensic analysis.
   • Secure web server, PHP and DB logs.
2. Contain and isolate
   • Put site into maintenance mode or restrict access to trusted IPs while investigating.
   • Suspend or force password resets for accounts that showed suspicious activity.
   • Add strict WAF rules to block further malicious inputs.
3. Assess scope
   • Identify which endpoints and queries were used.
   • Search for suspicious admin users, changed files, unknown scheduled tasks, or unexpected uploads.
4. Remediate and recover
   • Update the vulnerable plugin to 2.0.5 immediately (after backups).
   • Rotate administrator passwords, API keys, and any credentials stored in the database.
   • Replace modified files with clean copies from verified sources or backups.
   • If persistence is detected and you cannot remove all backdoors, rebuild from a clean backup.
5. Verify
   • Scan the site with reputable malware detection tools and re‑run integrity checks.
   • Monitor closely for recurrence for several days after restoration.
6. Notification and follow up
   • If sensitive data was exposed, follow legal and regulatory notification obligations in your jurisdiction (Hong Kong and others as applicable).
   • Document the incident and update processes to reduce recurrence.

Long‑term hardening and developer guidance

Address root causes and strengthen development and operational practices:

• Least privilege: Limit role assignments and remove unused accounts. Only grant Subscriber or higher where necessary.
• Secure coding: Never treat user input as identifiers or SQL fragments. Use whitelists and map user options to fixed column names. Use parameterised queries for data values.
• Dependency management: Maintain an inventory of plugins, subscribe to vulnerability notifications, and automate updates where safe.
• Environment controls: Harden file permissions and use reproducible deployments.
• Monitoring and logging: Centralise logs and alert on anomalous patterns (e.g., unusual orderby usage).
• Backups: Ensure frequent, immutable off‑site backups and test restores regularly.
• Code review: Review third‑party plugins before deployment and limit plugin use to actively maintained, reputable projects.

How managed security services can help

If you use a managed security service or WAF provider, they can act as a stopgap while you patch. Typical benefits (vendor‑neutral):

• Deploy virtual patches to block exploit payloads at the edge before requests reach your site.
• OWASP Top 10 coverage to reduce many common injection vectors.
• Malware scanning and file integrity checks to detect post‑exploit changes.
• Rate limiting, bot management and behavioural controls to slow automated exploitation attempts.
• Incident support and logging to help investigate and recover from incidents.

Choose a provider based on track record, ability to tune rules for your application, and transparency of logging and forensics.

Practical checklist — step by step

Quick prioritised checklist:

• – Identify sites running CBX Bookmark & Favorite.
• – Update CBX Bookmark & Favorite to 2.0.5 on every site (or uninstall if unused).
• – If you cannot update immediately: enable virtual patching in your WAF or apply equivalent WAF rules that validate the orderby parameter.
• – Disable self‑registration if not required; audit Subscriber accounts.
• – Take full backups (files + DB) before making changes.
• – Scan site for modified files and suspicious accounts; check recent DB changes.
• – Rotate sensitive keys and reset administrator credentials if suspicious activity is detected.
• – Monitor logs and alerts for recurring attempts for several days after remediation.
• – Document remediation steps and update your patch management process.

Closing thoughts

Authenticated SQL injection is particularly dangerous because ordering and similar inputs are often treated as benign by developers. This disclosure highlights the need to validate every user‑controllable input and to maintain rapid update and containment procedures.

If you manage multiple WordPress installations, treat this as a high priority: update to CBX Bookmark & Favorite 2.0.5 immediately and use well‑tuned WAF rules as a temporary mitigation if updates cannot be applied at once.

For hands‑on assistance: engage a trusted security consultant or managed service that can tune rules and help with incident response and recovery.

— Hong Kong Security Expert