# CVE-2026-104732: Advanced IP Blocker <= 8.13.13 - Unauthenticated Authentication Bypass via Missing Step-1 Binding to 2FA Login Handler

> Unauthenticated attackers can bypass 2FA and gain administrator access by brute-forcing TOTP codes due to missing step-1 validation in the Advanced IP Blocker plugin.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Oct 2026
- **Updated:** 11 Oct 2026
- **Also known as:** GHSA-pw6h-rjh8-7grw

## What is CVE-2026-104732?

CVE-2026-104732 is a critical authentication bypass vulnerability in inilerm Advanced IP Blocker, published on 10 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-104732?


## How do I fix CVE-2026-104732?

No fix has been published for CVE-2026-104732 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-104732 being exploited?

There is no known exploitation of CVE-2026-104732 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104732 and fix it if it is affected.

What it is: CVE-2026-104732 is a critical authentication bypass vulnerability in inilerm Advanced IP Blocker, published on 10 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-104732 in the wild and no public exploit code.

Affected product: inilerm Advanced IP Blocker. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-104732/ (Markdown: https://insights.sbomify.com/CVE-2026-104732/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104732
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104732
- OSV: https://osv.dev/vulnerability/CVE-2026-104732

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104732/
Summaries are generated and may contain mistakes; the official description above is the record.