CVE-2026-104732: Auth Bypass (CVSS 9.8)

Description

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.

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CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0047

Probability of exploitation

0.40%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-287 Improper Authentication

References

Other References

https://plugins.trac.wordpress.org/browser/advanced-ip-blocker/tags/8.13.13/includes/class-advaipbl-2fa-manager.php#L71 https://plugins.trac.wordpress.org/browser/advanced-ip-blocker/tags/8.13.13/includes/class-advaipbl-main.php#L519 https://plugins.trac.wordpress.org/browser/advanced-ip-blocker/tags/8.13.13/includes/class-advaipbl-main.php#L6875 https://plugins.trac.wordpress.org/browser/advanced-ip-blocker/tags/8.13.13/includes/class-advaipbl-main.php#L6912 https://plugins.trac.wordpress.org/browser/advanced-ip-blocker/tags/8.13.13/includes/class-advaipbl-main.php#L7022 https://plugins.trac.wordpress.org/changeset/3725139/advanced-ip-blocker/trunk/includes/class-advaipbl-main.php https://www.wordfence.com/threat-intel/vulnerabilities/id/d080845b-6814-4b10-a3ab-1f5aa1d09132?source=cve

Frequently Asked Questions

What is CVE-2026-104732? +

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. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-104732? +

CVE-2026-104732 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0047, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-104732? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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