---
title: "CVE-2026-103646: Ultimate Multisite WordPress - Authentication Bypass"
description: "Ultimate Multisite WordPress plugin < 2.17.0 contains an authentication bypass caused by inconsistent email normalization in duplicate-account check, letting unauthenticated attackers log in as existing users, exploit requires checkout form without password and target account without customer record."
url: https://panop.io/threat-heartbeat/CVE-2026-103646/
---

# CVE-2026-103646 Ultimate Multisite WordPress - Authentication Bypass

Ultimate Multisite WordPress plugin < 2.17.0 contains an authentication bypass caused by inconsistent email normalization in duplicate-account check, letting unauthenticated attackers log in as existing users, exploit requires checkout form without password and target account without customer record.

CVSS base score 9.8 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.44% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-103646)

## Details

Type

Authentication Bypass

Impact

Broken Authentication

CVSS vector

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

Published

8 October 2026

Updated

15 October 2026

Weakness

[CWE-287](https://cwe.mitre.org/data/definitions/287.html)

## Vendor fix

Update to version 2.17.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-103646](https://nvd.nist.gov/vuln/detail/CVE-2026-103646)
- [https://wpscan.com/vulnerability/a05da0ad-5d92-406f-b182-b3ed1f8389f3/](https://wpscan.com/vulnerability/a05da0ad-5d92-406f-b182-b3ed1f8389f3/)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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