Advanced IP Blocker <= 8.13.13 - Unauthenticated Authentication Bypass via Missing Step-1 Binding to 2FA Login Handler
The Advanced IP Blocker plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 8.13.13 The vulnerability exists because handle_login_action() performs no server-side check — via transient, session marker, or equivalent — that a requester completed step-1 password authentication before processing a step-2 TOTP submission for the POSTed user_id; compounding this, an error branch in the function unconditionally mints a fresh advaipbl-2fa-interim-{user_id} nonce and delivers it in a Location header to any unauthenticated caller, after which display_2fa_login_form_step_2() renders a valid advaipbl-2fa-verify-{user_id} nonce in HTML — both nonces computed against a fixed uid=0 empty-session context and therefore fully reusable by the attacker across subsequent requests. This makes it possible for unauthenticated attackers to bypass authentication entirely for any 2FA-enabled account, including administrators, by brute-forcing an unthrottled 6-digit TOTP code (no attempt counter, no account lockout, and no wp_login_failed firing) and receiving a fully authenticated session cookie via wp_set_auth_cookie without ever supplying the account password, resulting in complete site takeover. Exploitation requires only a known user_id for an account that has the plugin's 2FA feature enabled.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| WordPress plugin | Advanced IP Blocker | <= 8.13.13 | 8.13.14 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-287- Platform
- WordPress
- Package
Advanced IP Blocker- Disclosed
- 09.10.2026
- Updated
- 11.10.2026 10:23
Sources and licenses
Wordfence Intelligence - d080845b-6814-4b10-a3ab-1f5aa1d09132 - Wordfence Intelligence
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Copyright 2012-2026 Defiant Inc.
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Vulnerability history: Advanced IP Blocker
All published vulnerabilities of this package (WordPress plugin), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 05.2026 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 1
Disclosures per year
- 2026: 2
-
Advanced IP Blocker <= 8.13.13 - Unauthenticated Authentication Bypass via Missing Step-1 Binding to 2FA Login Handler this entry
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