Urgent: Privilege Escalation in Truelysell Core (≤ 1.8.7) — What WordPress Site Owners Must Do Now

Published: 16 Feb 2026   |  
Severity: High (CVSS 9.8) — CVE‑2025‑8572   |  
Affected: Truelysell Core plugin versions ≤ 1.8.7   |  
Fixed in: Truelysell Core 1.8.8

I am a Hong Kong–based WordPress security practitioner. A critical, publicly disclosed registration‑related privilege escalation exists in the Truelysell Core plugin (versions up to and including 1.8.7). The vulnerability allows unauthenticated attackers to create or elevate user accounts to high privilege levels via the registration flow, and can lead to full site takeover if exploited.

Quick summary (if you only read one thing)

• Vulnerability type: Unauthenticated privilege escalation via registration (OWASP A7: Identification and Authentication Failures).
• Impact: An unauthenticated attacker can manipulate the registration endpoint to create or elevate a user account with administrative privileges, enabling site takeover.
• Affected versions: Truelysell Core ≤ 1.8.7.
• Fix: Update to Truelysell Core 1.8.8 (or later) immediately.
• If you cannot update immediately: disable public registrations, block registration endpoints at the server/WAF level, and search for newly created privileged users.
• Proactive checks: search for recently created admin accounts, review logs for registration POSTs, and run a full malware scan.

為什麼這個漏洞如此危險

Unauthenticated privilege escalation is top‑priority for three reasons:

1. No authentication hurdle: Attackers can trigger the vulnerability remotely without valid credentials, allowing mass automated scanning and exploitation.
2. Rapid lateral movement: If an attacker gains administrator-level access they can install backdoors, create persistent admin users, change site options, inject malicious code, and exfiltrate data.
3. 自動化利用： WordPress plugin vulnerabilities are actively scanned and exploited by bots. A published CVE and critical score (9.8) mean widespread attempts are likely within hours or days.

Treat this as an active emergency: patch quickly, mitigate immediately if you cannot update, and assume compromise if suspicious indicators appear.

Technical overview — how the attack works (high level)

Public reports indicate the registration endpoint accepts input that results in account creation or modification without proper validation or privilege checks. Common underlying causes include:

• A registration/AJAX endpoint accepting a 角色 或 user_role parameter without validation.
• Missing nonce verification or server‑side capability checks for fields that affect privileges.
• Incomplete input validation that allows a requester to create an account with elevated capabilities or change an existing account’s role.

Attackers craft POST requests targeting the registration action with parameters to set the role to 管理員 (or a similar high privilege role), or leverage race conditions that promote a freshly created account. Because the endpoint is unauthenticated, anyone can send such a request. For safety, I will not publish proof‑of‑concept payloads here.

Indicators of Compromise (IoCs) — what to look for right now

• New administrator users created around or after the disclosure date.
• User accounts with unexpected elevated roles registered in a short time window.
• Sudden changes to site settings, permalinks, or site_url/home_url in the database.
• New plugins or themes installed and activated unexpectedly.
• Unknown mu‑plugins (must‑use) or persistent modifications in wp-content.
• Suspicious scheduled tasks (cron jobs) you did not create.
• Outbound connections from the server to unknown domains.
• Web server logs showing repetitive POSTs to registration endpoints, AJAX endpoints, or admin-ajax.php containing registration‑related parameters.
• Login spike anomalies or many failed logins from many IPs followed by a successful login on a newly created account.

If you observe any of the above, assume compromise and act accordingly (see the incident response section).

Immediate mitigation checklist (0–2 hours)

If your site uses the affected plugin and you cannot update immediately, perform these prioritized steps now. Do the first two immediately.

1. Update the plugin to 1.8.8 (or later) if possible. This is the definitive fix. Update now if you can.
2. If you cannot update immediately — disable user registration.
   • WordPress admin: Settings → General → uncheck “Anyone can register”.
   • Or use WP‑CLI:

     wp option update users_can_register 0

   Disabling registration prevents new accounts from being created while you prepare a proper patch.

3. Block registration endpoints at the server or WAF level.
   • Temporarily block requests to plugin-specific registration endpoints and known registration actions (for example, suspicious POSTs to admin-ajax.php with registration action names).
   • Add rate limits on POSTs to login/registration endpoints.
4. Force password resets and rotate credentials for administrators.
   • Reset passwords for all administrator accounts to strong, unique values.
   • Rotate any API keys or secrets stored in options or configuration files.
5. Scan for new admin users and remove suspicious accounts. Useful WP‑CLI commands:

   # List administrators
   wp user list --role=administrator --format=csv
   
   # Delete a malicious user by ID (reassign their content to user ID 1)
   wp user delete 123 --reassign=1

6. Strengthen authentication.
   • Enforce multi‑factor authentication (MFA) for all admin users.
   • Ensure user registration default role is Subscriber (if registrations are required later).
7. Enable rules to block suspicious registration payloads.
   • Block requests attempting to set role=administrator 或類似的情況。.
   • Block requests lacking expected nonces or with anomalous header patterns.

If you have an active application firewall or WAF already, ensure relevant rules are enabled and in blocking mode for registration tampering patterns.

Detailed detection and cleanup steps (2–24 hours)

If you suspect compromise, follow these steps in order. The guidance assumes you have SSH and WP‑CLI access; if not, request them from your host or work with a security professional.

1. 隔離網站
   • 將網站設置為維護模式。.
   • Block inbound traffic except trusted admin IPs while investigating.
2. Collect forensic data
   • Export web server access and error logs for the last 30 days (or since suspected compromise).
   • Export a database dump (do not modify it before backup).
   • Record timestamps for suspicious registrations, file modifications, and cron entries.
3. Search for new admin accounts

   # list users with roles and registration dates
   wp user list --fields=ID,user_login,user_email,roles,user_registered --format=csv | sort -t, -k5

   Look for suspicious user_registered timestamps.

4. Review recent file changes

   # show files changed in last 7 days in wp-content
   find wp-content -type f -mtime -7 -ls

   Investigate newly added PHP files, especially under wp-content, wp-content/mu-plugins, ，以及 wp-content/uploads.

5. Search for injected code

   grep -R --color -nE "(base64_decode|eval\(|shell_exec\(|system\()" wp-content

   Inspect results carefully — some plugins legitimately use these functions, but unexpected occurrences are red flags.

6. 檢查排程任務

   wp cron event list --fields=hook,next_run --format=csv

   Look for unknown hooks or tasks scheduled by unknown plugins.

7. Reset secrets
   • Rotate WordPress salts in 9. 或使用使會話失效的插件。在可行的情況下強制執行雙因素身份驗證。.
   • Rotate any API keys stored in site options, payment gateways, or third‑party services.
8. Perform a full malware scan

   Run a reputable malware scanner to detect webshells, injected code, and anomalous files.

9. 如有必要，從乾淨的備份中恢復
   • If you confirm persistent backdoors or compromise, restore from a clean backup taken before the breach.
   • After restore, apply the plugin update immediately and harden the site configuration.
10. Audit administrator actions

    Review change logs, file modifications, and plugin/theme installations around suspicious registration timestamps.

11. 加固和監控
    • Reinstate application firewall rules with strict logging.
    • Enable continuous monitoring and regular vulnerability scanning where possible.

If you need to find potentially malicious administrator users via SQL (advanced users only), you can use:

SELECT ID, user_login, user_email, user_registered
FROM wp_users
WHERE ID IN (
  SELECT user_id FROM wp_usermeta WHERE meta_key = 'wp_capabilities'
  AND (meta_value LIKE '%administrator%' OR meta_value LIKE '%shop_manager%')
)
ORDER BY user_registered DESC;

Always back up the database before running manual SQL and take extreme care — incorrect modifications can break the site.

Recommended long-term fixes and hardening (24–72 hours and ongoing)

1. 保持所有內容更新 — WordPress core, themes, and plugins should be updated promptly. Test updates in staging if your site has complex customisations.
2. 最小特權 — Assign the minimum role necessary, remove unused administrator accounts, and periodically review roles.
3. Disable unnecessary registration — If you don’t need public registrations, keep registration disabled. If you do, enforce email verification, set default role to Subscriber, and consider manual review for new accounts.
4. Application layer protection — Deploy a WAF or web application protection layer to block malicious POSTs and automated scanners. Use rate limiting and IP/geo restrictions for registration and login endpoints.
5. Content integrity monitoring — Monitor unexpected file additions/modifications in wp-content. Maintain checksums for plugin/theme files and alert on changes.
6. Authentication hardening — Enforce MFA for privileged users and apply strong password policies with periodic rotation.
7. 日誌記錄和警報 — Keep detailed access logs and set alerts for suspicious events: admin account creation, plugin installs, or unexpected file changes.
8. 備份與恢復 — Maintain frequent encrypted backups stored separately from the server and test restore procedures regularly.
9. Vendor due diligence — Before installing plugins, check developer reputation, update cadence, and maintenance activity.
10. 虛擬修補 — Consider virtual patching (WAF rules) to block exploit attempts while scheduling immediate plugin updates.

Example WAF detection and rule patterns (practical)

For teams operating a WAF or server‑level rules, consider these detection patterns (test in monitor mode first):

• Block POST requests containing role=administrator, role=admin, user_role=administrator, etc., aimed at registration endpoints or admin-ajax.php.
• Block POSTs missing expected nonces or referer headers for registration endpoints.
• Rate limit POSTs to registration endpoints per IP.
• Block requests with suspicious user_agent strings or known scanner signatures.
• Block requests attempting to set user_status=active or parameters that bypass email verification logic.

Simple pseudo‑rule example:

IF method == POST AND request_path CONTAINS "admin-ajax.php" AND body MATCHES /(action=(register|tr_register)).*(role=(administrator|admin|super_admin|shop_manager))/i
THEN BLOCK and LOG

If you are already compromised — incident response playbook

1. 分類： Confirm the compromise using logs and forensic evidence.
2. 隔離： Put the site into maintenance mode and block external traffic.
3. 保留證據： Take full backups and copies of logs; do not overwrite data.
4. 根除：
   • Remove malicious users and backdoors.
   • Reinstall non‑custom plugins and themes from trusted sources.
   • Remove unknown files in wp-content.
5. 恢復： Restore from a clean backup if necessary, then rotate all credentials and update the plugin to 1.8.8 or later.
6. 事件後： Perform a root cause analysis, close the exploited vector, and implement monitoring and protections to prevent re‑exploitation. Notify affected parties if data exposure is suspected.

If the scope of compromise is unclear, engage an experienced incident response provider. Thorough cleanup is essential — attackers often leave multiple persistence mechanisms.

Practical commands and snippets (cheat sheet)

# Disable public registration
wp option update users_can_register 0

# List administrator users
wp user list --role=administrator --format=csv

# Force password reset for all admins (scripted; test before running)
wp user list --role=administrator --field=ID | xargs -n1 -I % wp user update % --user_pass=$(wp eval 'echo wp_generate_password(16);')

# Remove suspicious user by login
wp user delete suspicious_user --reassign=1

# Dump recent users (last 30 days)
wp db query "SELECT ID, user_login, user_email, user_registered FROM wp_users WHERE user_registered >= DATE_SUB(NOW(), INTERVAL 30 DAY);" --skip-column-names

# Find PHP files modified in last 7 days
find . -type f -name "*.php" -mtime -7 -print

# Search for potential webshell patterns
grep -R --color -nE "(eval\(|base64_decode\(|gzinflate\(|preg_replace\(.*/e|\$\_REQUEST\['.*'\])" wp-content

Best practices for plugin authors and site owners (developer perspective)

• Never trust user input for role or capability assignment; validate against a server‑side whitelist and require capability checks for privileged changes.
• Require and verify nonces for registration forms.
• Ensure registration flows enforce verification (email confirmation) and never create privileged accounts via automated registration.
• Use WordPress APIs (wp_create_user(), wp_insert_user()) with explicit role checks and avoid relying on client‑supplied 角色 參數。.
• Maintain a security release process and communicate promptly with your community.

最終檢查清單——您現在應該做的事情

1. Check if your site runs Truelysell Core and what version. If ≤ 1.8.7, treat it as vulnerable.
2. If possible, update Truelysell Core to 1.8.8 immediately.
3. 如果您現在無法更新：
   • Disable registration (Settings → General → uncheck “Anyone can register”).
   • Enable server/WAF rules to block registration tampering.
   • Force password resets for admin accounts and enforce MFA.
   • Audit users and remove any unexpected admin accounts.
4. Run a full malware scan and inspect recently modified files.
5. Monitor logs for suspicious registration POSTs and new admin account activity.
6. Consider temporary virtual patching or targeted WAF rules while you update.

結語

Registration flows and user management are high‑value attack surfaces. A single unchecked parameter or missing validation can allow an attacker to bypass authentication entirely and take control of a site. Prompt action — updating the plugin, tightening registration, enabling protective rules, and performing forensic checks — will remove the immediate risk for most sites. If you need assistance assessing an incident, engage a trusted security professional.

— 香港安全專家