Live Exposure Defense: From CVE to Confirmed Exposure in 12 Hours – See more

Back
New CVE Detected

CVE-2026-75957 – Unauthenticated Authentication Bypass – Ultimate Multisite WordPress Plugin ≤ 2.15.

Be the first to know when new zero-days emerge:

Subscribe to Email Alerts
Subscribe to RSS Feed

Summary

CVE-2026-75957 is a critical authentication bypass vulnerability in the Ultimate Multisite – WordPress Multisite SaaS & WaaS Platform plugin (by superdav42), affecting all versions up to and including 2.15.0. The flaw allows an unauthenticated attacker who knows a target’s email address to log in as that existing WordPress user — including a Network Super Admin — without any credentials. The vulnerability carries a CVSS v3.1 base score of 9.8 (Critical).

Technical details

  • Root cause: the publicly reachable wu_ajax_nopriv_wu_validate_form AJAX handler accepts a freely obtainable checkout nonce and processes the checkout_form parameter.
  • Trigger condition: supplying checkout_form=wu-finish-checkout causes get_validation_rules() to discard all validation rules while finish_checkout_form_fields() returns an empty step list, forcing is_last_step() to evaluate true and routing the request straight into full order processing.
  • Downstream flaw: maybe_create_customer() then resolves an attacker-supplied email_address to an existing WordPress user ID without verifying authentication or account ownership, and the plugin establishes a session via wp_set_auth_cookie().
  • Attack vector: Network, no privileges or user interaction required (CWE-287, Improper Authentication).
  • Impact: full account takeover of any targeted existing user whose account lacks a pre-existing Ultimate Multisite customer record — notably Network Super Admins on fresh installs, or administrators/editors created before Ultimate Multisite was configured.

Affected software

  • Ultimate Multisite – WordPress Multisite SaaS & WaaS Platform (superdav42), all versions up to and including 2.15.0

Severity

  • CVSS v3.1 Base Score: 9.8 (Critical)
  • Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Mitigation and recommended actions

  • Immediate: upgrade Ultimate Multisite to version 2.15.1 or later, where the checkout validation/order-processing flow has been corrected.
  • If a patch cannot be applied immediately: restrict or disable public access to the plugin’s checkout/AJAX endpoints at the web application firewall or reverse proxy level, and monitor authentication logs for unexpected logins to administrator or long-dormant accounts.
  • After patching, review recent login activity for Network Super Admin and other privileged accounts for signs of prior exploitation.

References

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report

How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report
Close

Subscribe to Threat Center RSS

Copy/paste the link below into your preferred RSS reader or follow these instructions to subscribe to Slack alerts.

Open RSS feedSlack setup instructions

Close

Get Real-Time CVE Alerts to Your Email

Be the first to know when new zero-days emerge