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CVE-2026-39524 – Unauthenticated Broken Access Control / Payment Bypass – Masteriyo LMS WordPress…

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Summary

CVE-2026-39524 is a high-severity Unauthenticated Broken Access Control vulnerability (CWE-862: Missing Authorization) in the Masteriyo – LMS WordPress plugin by ThemeGrill, affecting all versions up to and including 2.1.5. Rated CVSS 7.5 (High), the flaw allows any unauthenticated remote attacker to bypass payment authorization controls, enabling unauthorized manipulation of order or payment state without completing a valid transaction.

Technical details

  • Root cause: Missing authorization checks (CWE-862) on a payment-related processing function within the plugin, allowing requests to bypass access controls without authentication or valid payment verification.
  • Trigger conditions: No authentication, credentials, or user interaction are required. Any remote attacker can trigger the vulnerability directly over a standard HTTP/HTTPS request.
  • Attack vector: Network-based (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N).
  • Impact: High integrity impact (I:H) — unauthenticated attackers can perform unauthorized payment bypass operations, compromising the integrity of order and payment processing. No confidentiality (C:N) or availability (A:N) impact is present.

Affected software

  • Masteriyo – LMS WordPress plugin by ThemeGrill, all versions ≤ 2.1.5

Severity

  • CVSS v3.1 Base Score: 7.5 (High)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Mitigation and recommended actions

  • Immediate: Update Masteriyo – LMS to version 2.1.6 or later, which contains the vendor-issued fix for this vulnerability.
  • Administrators should verify their installed plugin version via the WordPress dashboard under Plugins → Installed Plugins and apply the update immediately.
  • If immediate patching is not possible, consider applying WAF rules or network-level controls to restrict unauthenticated access to plugin endpoints until the patch can be deployed.

IONIX Status

The IONIX research team is tracking ongoing exploitation attempts and recommends immediate patching. Potentially affected assets are outlined in this post.

References

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