Tên plugin	Custom Query Shortcode
Type of Vulnerability	Đường dẫn đi qua
CVE Number	CVE-2025-8562
Tính cấp bách	Thấp
CVE Publish Date	2025-08-25
Source URL	CVE-2025-8562

Urgent: Directory Traversal in ‘Custom Query Shortcode’ (<= 0.4.0) — What WordPress Site Owners Need to Know and Do Now

Tác giả: WP‑Firewall Security Team
Ngày: 2025-08-26

Executive summary

A directory traversal vulnerability (CVE‑2025‑8562) has been disclosed in the WordPress plugin “Custom Query Shortcode” affecting versions <= 0.4.0. An authenticated user with Contributor privileges (or higher) can manipulate the plugin’s lens parameter to traverse directories on the server and potentially read files outside the intended plugin directory. The issue has been fixed in version 0.5.0.

As maintainers of a WordPress web application firewall (WAF) and a managed WordPress security service, we want to explain what this vulnerability means, how attackers may try to exploit it, how to detect attempted or successful exploitation, immediate and longer‑term mitigations, and how WP‑Firewall can help protect your site — including our Free plan option.

This advisory is written for site owners, administrators, and security-conscious developers. It intentionally avoids showing weaponizable exploit code but provides the operational detail you need to make fast, informed decisions.

What is the vulnerability?

• Affected plugin: Custom Query Shortcode
• Vulnerable versions: <= 0.4.0
• Fixed in: 0.5.0
• Vulnerability type: Directory Traversal (local file disclosure / information leakage)
• CVE: CVE‑2025‑8562
• Required privilege to exploit: Contributor (authenticated)
• Reported by: Muhammad Yudha (credited)

In short, the plugin accepts a lens parameter (used in its shortcode) which is not properly validated or sanitized. By providing crafted values for that parameter, an authenticated contributor can cause the plugin to reference files outside the intended path — enabling attackers to enumerate or read files from directories they shouldn’t access.

Why directory traversal matters

Directory traversal vulnerabilities enable attackers to request files that the application was never intended to serve (for example, configuration files, backup copies, theme or plugin source files, or private keys if they are accessible to the web server). The direct impact is information disclosure:

• Access to secrets, API keys, database credentials stored incorrectly in files.
• Insight into site structure and installed software that helps follow‑on attacks.
• Exposure of private uploads or backups that may contain PII or credentials.

While directory traversal alone may only provide read access, it commonly leads to further compromise when chained with other weaknesses (e.g., sensitive config files reveal DB credentials, which are then used to pivot).

Who is at risk?

Any WordPress site running the Custom Query Shortcode plugin at version 0.4.0 or earlier is vulnerable if:

• The plugin is active, and
• The site allows user accounts with the Contributor role (or higher), or attacker has gained Contributor-level access through another weakness.

Many sites permit self-registration or use third‑party plugins that assign user roles; an attacker who can register or get a Contributor account — or who compromises an existing account — can exploit this issue.

How an attacker can abuse this (high level)

1. Attacker obtains an account with Contributor privileges. This can be by:
   • Registering (if the site allows user registration).
   • Social engineering / credential stuffing against weak passwords.
   • Compromising a less‑privileged admin/editor account via another flaw.
2. The attacker submits a page or post containing the vulnerable shortcode and supplies a specially crafted lens parameter that includes directory traversal sequences (e.g., ../ and encoded variants).
3. The plugin processes lens and resolves a file path using the user-supplied value without sufficient sanitization.
4. The server returns file contents or errors that leak path information, enabling enumeration and exfiltration of files the webserver process can read.

We are not publishing exploit strings; the point is to show the logical flow and to help defenders detect and mitigate.

Attack prerequisites and limitations

• Privileged requirement: Contributor or higher (authenticated). Anonymous attackers cannot trigger the vulnerability directly unless the site misconfigures permissions or uses the plugin in a context where anonymous input is accepted by the shortcode.
• File read is limited to files readable by the web server user (e.g., www-data). Files owned by root or protected at OS level may be safe.
• The vulnerability does not automatically grant code execution (remote code execution), but reading sensitive files (wp-config.php, .env, backup archives) substantially increases the attacker’s options.

Immediate actions (what you should do now)

If you manage a WordPress site running this plugin, follow these steps immediately:

1. Verify plugin installation and version:
   • Dashboard: Plugins → Installed Plugins → locate “Custom Query Shortcode”.
   • WP‑CLI: wp plugin list | grep custom-query-shortcode
2. Update the plugin to 0.5.0 or later as soon as possible:
   • Dashboard: Plugins → Update (select the plugin and update)
   • WP‑CLI: wp plugin update custom-query-shortcode
3. If you cannot update immediately:
   • Deactivate the plugin until you can update.
   • If the plugin is required, remove it until a safe upgrade is available.
4. Review and limit user roles:
   • Review all user accounts that have Contributor or higher privileges.
   • Remove or downgrade any unexpected accounts.
   • Enforce strong passwords and enable 2‑factor authentication for authors or higher.
5. Scan for indicators of compromise:
   • Check access logs for requests that include lens= or suspicious POST data.
   • Search for unusual file reads or downloads (grep for wp‑config.php reads, backup file access).
   • Run a full site malware scan and compare core/plugin/theme files to clean copies.
6. Rotate secrets if you suspect leakage:
   • Change database credentials if you suspect wp-config.php was accessed.
   • Rotate API keys or tokens found in files.
   • Consider rotating SMTP, payment gateway, or other third‑party keys.

How to detect exploitation attempts

Look for suspicious patterns in your web server access logs, application logs, and WordPress activity logs.

Search examples (run as root or a user with log access):

• Apache / Nginx access log (compressed and rotated files included):
  • grep -i "lens=" /var/log/apache2/*access* /var/log/nginx/*access* | less
  • zgrep -i "lens=" /var/log/apache2/*.gz
• WordPress debug and audit logs:
  • Look for content submissions that include the shortcode with unusual lens values.
  • Check user activity logs for Contributors creating posts/pages around the time of suspicious requests.

Audit patterns to watch for:

• Requests that include percent-encoded traversal sequences, e.g. %2e%2e%2f hoặc %2e%2e/.
• Requests that reference filenames outside expected plugin directories (errors returning 200 with file contents).
• Unexpected 200 responses for requests that should return 404 or 403.

Log message examples to look for:

• GET /some-post?lens=../../wp-config.php
• POST /wp-admin/admin-post.php body includes lens=../../

Note: the exact parameter name is lens. Monitoring for any requests that include that parameter with dot-dot patterns is a valuable quick detection rule.

WAF and virtual patching guidance

If you run a WAF (network layer or application layer), create a targeted rule to reduce risk immediately while you update:

Recommended detection and block criteria (conceptual):

• Block requests where any parameter named lens (or any parameter used by the plugin) contains:
  • Unescaped directory traversal sequences such as ../, ..\ or their URL-encoded equivalents (%2e%2e%2f, %2e%2e/, %2e%2e%5c, etc.)
  • Path separators combined with .. patterns (after URL decoding)
• Block requests attempting to access well-known sensitive files via query or form parameters (e.g., wp-config.php, .env, id_rsa, config.php, .git/).

Example detection pseudo‑regex (for WAFs that accept PCRE; adapt before use):

(^|[&?])lens=.*(\.\./|\.\.\\|%2e%2e%2f|%2e%2e%5c)

Important: Test WAF rules in detection mode first to avoid false positives. Some legitimate plugins or themes may use dot characters for other reasons.

WP‑Firewall customers: our WAF already has targeted signatures that block directory traversal attempts in query parameters and shortcodes, and our virtual patching can be deployed immediately to protect sites that cannot update right away.

Hardening the site beyond the immediate fix

Applying the vendor patch or deactivating the plugin must be the first step. Once that is done, implement these best practices to reduce future exposure:

1. Principle of least privilege for user accounts:
   • Only give Contributor or higher roles to people who actually need them.
   • Consider using a custom role with narrowly-scoped capabilities for content contributors.
2. Harden PHP and the server:
   • Enable open_basedir restrictions for the web server/PHP to limit filesystem access to the necessary WordPress directories.
   • Disable dangerous PHP directives if you don’t need them: disable allow_url_include, disallow execution of PHP files in the uploads directory via server config.
3. File and directory permissions:
   • Ensure wp-config.php is not web‑accessible where possible (move configuration if using environment files, but be careful with WordPress expectations).
   • Set correct permissions: directories 755, files 644 in most Linux environments; sensitive files should be readable only by the webserver user where practical.
4. Disable directory listing:
   • Ensure your web server configuration does not allow directory listing for document roots or upload folders.
5. Remove or replace unused plugins and themes:
   • Inactive plugins can still carry risk if an attacker can upload files into their directories. Delete plugins you are not using.
6. Monitor integrity:
   • Use file integrity monitoring to detect unexpected changes to core, plugin, and theme files.
   • Schedule regular automated scans for malware or unexpected file additions.
7. Registration policy:
   • If you do not need open user registration, disable it (Settings → General → Membership).
   • If registrations are required, add moderation or require a trusted vetting process.
8. Authenticate and authorize:
   • Use email verification and moderate new accounts.
   • Enable two‑factor authentication for any roles with the ability to publish or upload files (Author, Editor, Administrator).

For developers: secure handling of inputs and shortcodes

If you develop or maintain WordPress plugins or shortcodes, consider these coding controls to prevent similar issues:

• Never use user-supplied input directly to build filesystem paths. Always resolve to a canonical base directory and validate that the resulting path is inside the intended directory (use realpath() and confirm the prefix matches).
• Sanitize and normalize all parameters: URL decode before validation, then reject values containing dot‑dot segments, absolute path tokens, or null bytes.
• Use safe include/load patterns — avoid dynamic includes based solely on user input.
• Use capability checks before performing any file operations triggered by user input.
• Keep dependency libraries up to date and perform regular security reviews on code that handles file I/O.

If you believe your site was breached

Follow an incident response checklist:

1. Isolate:
   • If you observe clear signs of compromise, temporarily take the site offline or enable maintenance mode to stop further damage.
2. Preserve logs:
   • Collect and back up logs (access, error, application) to preserve forensic evidence.
3. Change credentials:
   • Reset all WordPress admin/editor accounts and database credentials if you suspect leakage.
   • Revoke API keys that may have been exposed.
4. Clean and restore:
   • Restore from a clean backup taken before the compromise if available.
   • If you can’t restore, perform a full cleanup — replace WordPress core, theme, and plugin files from known clean sources, and remove unknown files.
5. Perform post‑mortem:
   • Identify how the attacker gained access (vulnerability, stolen credential, etc.) and remediate the root cause so the same vectors are closed.
6. Notify stakeholders:
   • If customer data may have been exposed, follow your legal and contractual obligations for disclosure.

Practical detection recipes and commands

Below are safe, non‑destructive commands to check for evidence of exploitation. Run them from a shell on your web server as a privileged user that can read logs.

Search access logs for lens parameter usage:

• grep -i "lens=" /var/log/apache2/*access* /var/log/nginx/*access* | less
• zgrep -i "lens=" /var/log/apache2/*.gz

Search posts and pages for suspicious shortcodes (via WP‑CLI):

• wp post list --post_type=post,page --format=ids | xargs -n1 -I% wp post get % --field=post_content | grep -i "lens=" -n

Search webroot for new or modified files in the last 30 days:

• find /var/www/html -type f -mtime -30 -ls

Look for reads of wp-config.php in logs (indication of attempted disclosure):

• grep -i "wp-config.php" /var/log/apache2/*access* /var/log/nginx/*access*

Note: adapt paths to your environment.

How WP‑Firewall protects you

As a WordPress firewall and managed security provider, we do three things that matter in incidents like this:

1. Managed WAF rules: We deploy signature rules for directory traversal patterns (dot‑dot URL‑encoded and raw), and specific rules that watch for parameters commonly abused by vulnerable plugins (including shortcode parameters like lens). These rules can block attempts before they reach PHP.
2. Virtual patching: For customers on our managed plans (and available to Free plan users in detection mode), we can apply virtual patches that stop the exploitation path even when an official plugin update hasn’t yet been applied site‑side. Virtual patches are applied at the proxy/WAF level and are non‑intrusive.
3. Continuous monitoring and automated alerts: We monitor for the indicators described above (suspicious lens usage, file reads, anomalous responses) and alert site owners with remediation steps.

We also provide a malware scanner and incident support workflows to help you recover if you suspect compromise.

Start with Essential Protection — WP‑Firewall Free Plan

If you want an immediate and lightweight layer of protection while you patch and harden, consider our Free plan. It includes essential protections that reduce the risk from vulnerabilities like this:

• Managed firewall with rule updates
• Unlimited bandwidth (no hidden throttles)
• Web Application Firewall (WAF) that blocks common attack patterns (including directory traversal)
• Malware scanner to detect suspicious files and modifications
• Giảm thiểu 10 rủi ro hàng đầu của OWASP

Try WP‑Firewall Free Plan: https://my.wp-firewall.com/buy/wp-firewall-free-plan/

(Free plan users can quickly enable core protections and receive real‑time blocking for patterns that target vulnerable plugins, giving you breathing space to update and investigate.)

Long‑term risk reduction: policies and process

Fixing single vulnerabilities quickly helps, but to reduce future risk consider these process changes:

• Inventory and exposure management:
  • Maintain a current inventory of plugins and themes in use.
  • Track version numbers and subscribe to security advisories for high‑risk components.
• Scheduled maintenance windows:
  • Schedule and automate safe plugin updates where possible.
  • Test updates in staging before production.
• Access governance:
  • Review user roles quarterly and remove stale accounts.
  • Use just‑in‑time access for project contributors where practical.
• Secure development lifecycle for custom code:
  • Run SAST (static analysis) and peer code reviews for all code that deals with files or user input.
  • Harden third‑party integrations to avoid unexpected privilege escalation.

Frequently asked questions

Q: If my site allows user registration but assigns Subscriber by default, am I still at risk?
A: The vulnerability requires Contributor privileges. If your registration results in Subscriber or another low‑privilege role, that lowers direct risk. However, attacker account elevation via another plugin flaw or social engineering is still possible, so monitor registration and role assignments carefully.

Q: Does directory traversal mean the attacker can run commands on my server?
A: Not necessarily. Directory traversal primarily allows reading files accessible by the web server. However, the information obtained (database credentials, backup files, private keys) can be used as a stepping stone for privilege escalation or remote code execution.

Q: I already updated to 0.5.0. Do I still need a WAF?
A: Yes. Patching is essential, but a WAF provides immediate mitigation against zero‑day exploitation, automated attacks, and can reduce impact while you test and roll out patches site‑wide. Defense-in-depth is the right approach.

Closing notes

Directory traversal issues like the one discovered in Custom Query Shortcode are a common class of vulnerabilities with a predictable exploitation pattern. The safe, practical steps are:

1. Update the plugin to 0.5.0 immediately (or deactivate/remove it until you can update).
2. Audit Contributor and higher‑privileged accounts and tighten user provisioning.
3. Monitor logs for suspicious lens usage and signs of file reads that shouldn’t happen.
4. Apply WAF rules (or enable virtual patching) to block traversal attempts until the plugin is patched.
5. Harden server configuration (open_basedir, permissions, disable directory listing) and follow secure development practices.

If you want us to quickly assess exposure on your site or deploy virtual patches to stop exploitation attempts while you update, WP‑Firewall can help. Start with our Free plan to get immediate protection and then consider a managed plan for continuous virtual patching, automated malware removal, and dedicated support.

Stay safe — treat plugin updates and account governance as first‑class citizens of your site security program.