Urgent: Two-Factor (2FA) Email Plugin Vulnerability (CVE-2025-13587) — Immediate Steps for WordPress Site Owners

Author’s note: written from the perspective of a Hong Kong security practitioner—direct, practical and focused on what to do now. This advisory is aimed at WordPress site owners, developers and operations teams who need clear actions rather than theoretical detail.

Executive summary

• Vulnerable plugin: Two Factor (2FA) Authentication via Email — versions ≤ 1.9.8.
• Patched in: 1.9.9 — update immediately if you use this plugin.
• CVE: CVE-2025-13587.
• Impact: Broken authentication / two-factor bypass. An unauthenticated attacker can bypass the second factor and may achieve administrative access.
• CVSS (reported): 6.5 — high severity.
• Urgency: High. Treat as a priority for any public-facing WordPress site using the plugin.

What the vulnerability means (high-level)

Email-based 2FA depends on properly generated, bound and single-use tokens. CVE-2025-13587 is a token handling weakness where tokens can be accepted without sufficient checks for ownership, session context or freshness. Practically, that means an unauthenticated request can sometimes be crafted so the server accepts a token and proceeds as if the second factor was satisfied.

Why this is dangerous for WordPress sites

WordPress powers many business-critical sites in Hong Kong and globally—ecommerce, membership, corporate and government-facing pages. If an attacker bypasses 2FA, consequences include:

• Full site takeover (create admin users, install backdoors, modify content).
• Data theft (user databases, order/customer PII).
• Distribution of malware or abuse of reputation for phishing/spam.
• Operational downtime, reputational damage and potential regulatory exposure.

How attackers may exploit this in the wild

Typical exploitation pattern:

• Automated scanners locate sites with the vulnerable plugin and probe plugin endpoints.
• Attackers submit crafted or replayed token values to bypass verification logic.
• Successful bypass may be combined with credential-stuffing or username enumeration to gain higher-value access.
• Once admin access is achieved, attackers commonly create persistent backdoors (new admin user, modified files, scheduled tasks).

Immediate actions — do these now

1. Update the plugin (first and foremost).

   Upgrade Two Factor (2FA) Authentication via Email to version 1.9.9 or later on every affected site. This is the definitive fix.

2. If you cannot patch immediately: deploy temporary virtual patches.

   Where immediate updates are impractical (large fleets, maintenance windows), apply temporary protections at your edge (WAF / reverse proxy / gateway) to reduce risk until you can patch:

   • Block unauthenticated POSTs to token-processing endpoints unless a valid session cookie is present.
   • Rate-limit token verification attempts per IP and per account.
   • Detect and block token replay patterns (same token used repeatedly from different sources).
   • Enforce referer/origin checks for token submission endpoints where feasible.
3. Harden authentication immediately.
   • Enable account lockouts or throttling on failed login attempts.
   • Avoid publicly exposed admin usernames; rename the default ‘admin’ user where possible.
   • Where available, use stronger second factors (TOTP or hardware tokens) for administrator accounts.
4. Hunt for signs of compromise.
   • Inspect admin user lists for unexpected accounts.
   • Check for recent plugin/theme installs, modified core files, unknown cron jobs or scheduled tasks.
   • Review access logs for suspicious POST/GET requests to plugin endpoints.
5. Rotate credentials and invalidate sessions.

   Force password resets for administrator accounts, rotate API keys and integration secrets, and invalidate active sessions after patching.

6. Scan and clean.

   Run a full malware scan. If you find evidence of intrusion, preserve forensic artifacts (logs, backups) before cleaning or rebuilding.

Detection: logs and indicators to review

Key artifacts to inspect:

• Web server access logs: repeated requests to plugin endpoints, parameters like token= or code=, anomalous POSTs with missing cookies or odd user agents.
• Application/plugin logs: unexpected authentication successes or warnings from token validation routines.
• WordPress sessions: admin sessions from unfamiliar IPs/geolocations or concurrent sessions from disparate locations.
• File system changes: new/modified PHP files in wp-content/plugins, wp-content/uploads, or modified core files.
• IoCs: new admin users with strange emails, unknown scheduled tasks, outbound connections to suspicious domains.

Example temporary WAF/virtual-patching rules (high-level)

Below are safe, conceptual rules you can implement in your edge controls. These avoid exposing exploit details but help block abuse:

• Block unauthenticated POSTs to 2FA endpoints unless a valid WordPress session cookie (wordpress_logged_in_) is present.
• Track token parameter values and block if the same token is reused more than once within a short period (e.g., 60 seconds).
• Rate-limit token verification attempts per IP and per username (e.g., throttle after 5 attempts in 5 minutes).
• Require Referer/Origin headers for token submission endpoints and reject requests without expected site host headers.
• Apply IP reputation checks and block requests from known scanners or botnets.

How to verify a site is clean after patching

1. Confirm the plugin version (Plugins → Installed Plugins shows version 1.9.9 or later).
2. Validate user accounts and permissions (no unexpected admin users).
3. Confirm no persistence mechanisms (unknown scheduled tasks, unauthorized plugin/theme files, modified core files).
4. Review logs for successful token bypasses—monitor for 7–14 days after patching.
5. Run a full malware scan (consider a second-opinion scan with a different engine).
6. Monitor connected systems (payment gateways, CRMs) for anomalous activity.

Incident response checklist (ordered)

1. Put the site into maintenance mode if feasible to limit further damage.
2. Capture forensic snapshots: files, database, full logs (preserve integrity when possible).
3. Rotate administrative passwords, API keys and integration secrets immediately.
4. Terminate active sessions.
5. Update the vulnerable plugin to 1.9.9 and update other components (themes, plugins, core).
6. Run malware scans and remove malicious files or restore from a verified clean backup.
7. Review logs to determine scope and timeline of the intrusion.
8. Remove unknown admin users and revoke suspicious access.
9. Reissue secrets used by external integrations (webhooks, payment services).
10. Notify affected stakeholders and customers if data exposure is likely.
11. Harden the site: WAF rules, rate limiting and strict file permissions.
12. Maintain heightened monitoring for 30–90 days.

Developer and maintainer guidance (practical)

• Prefer actively maintained plugins with frequent updates and a responsible disclosure contact.
• Reduce plugin count; remove unused plugins to shrink attack surface.
• Test updates in staging and roll out in a controlled manner for production-critical sites.
• Apply least privilege: limit administrative accounts and separate duties.
• Centralise logging outside the web host so attackers cannot easily erase evidence.
• Automate backups and periodically test restores.

Long-term recommendations to reduce authentication risk

1. Use TOTP or hardware tokens for administrative accounts rather than email-only 2FA.
2. Ensure tokens are cryptographically signed, single-use, tied to session and user IDs, and expire quickly.
3. Protect token endpoints with CSRF checks, origin validation and strict session handling.
4. Maintain a vulnerability management program for third-party components and track relevant CVEs.
5. Run periodic code audits for custom or in-house plugins.
6. Employ an edge WAF capable of virtual patching to reduce exposure windows between disclosure and patch deployment.

Forensics: what to capture if you suspect a breach

• Full web server access logs (Apache/nginx) covering the time window of interest.
• PHP error logs and any plugin-specific logs.
• Database snapshots (make a copy for analysis; do not modify originals).
• Filesystem snapshots of wp-content (plugins, themes, uploads).
• List of users, recent role changes, and recently installed/modified plugins.
• Network/firewall logs or flow data if available.

Store forensic artifacts offline and consult a forensic professional for targeted incidents.

Example non-exploit detection patterns

Use these heuristics when prioritising investigations (they are not definitive proof of exploitation):

• Repeated POSTs to /wp-content/plugins/*/verify or /wp-login.php?action=two_factor with varying token parameters.
• Token parameters with unexpected lengths or formats (very long or very short).
• Multiple successful admin logins from the same IP soon after token submissions where no normal login flow is visible.

FAQ (concise)

Q: I updated to 1.9.9 — do I still need a WAF?

A: Yes. Defence‑in‑depth is prudent: a WAF complements patching by protecting against other classes of attack and catching attempted exploitation while you remediate.

Q: Can I disable the plugin instead of updating?

A: If you do not need email 2FA, disabling or uninstalling the plugin is an acceptable temporary mitigation. Ensure administrators remain protected by other MFA methods.

Q: Will changing admin passwords stop an attacker who already bypassed 2FA?

A: Changing passwords helps, but if the attacker has already established persistence (backdoor accounts, modified files), passwords alone are insufficient. Follow the full incident response steps above.

Final concise checklist — do this now

• Confirm whether your site uses Two Factor (2FA) Authentication via Email.
• If yes, update plugin to 1.9.9 or later immediately.
• If you cannot update immediately, apply temporary edge/WAF rules to block token endpoint abuse.
• Rotate admin credentials and invalidate active sessions after patching.
• Scan for malware and review logs for signs of compromise.
• Audit admin users and remove suspicious accounts.
• Harden authentication and monitoring for the next 30–90 days.

If you are unsure about any step or you find signs of compromise, engage a trusted security consultant or incident response team promptly. Early containment and proper forensic capture are important—especially in high-risk environments.

Stay vigilant.