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New CVE Detected

CVE-2026-27543 – Unauthenticated Privilege Escalation – MStore API WordPress Plugin (≤ 4.20.0)

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Summary

CVE-2026-27543 is an unauthenticated privilege escalation vulnerability affecting the MStore API WordPress plugin (developed by FluxBuilder), versions up to and including 4.20.0. The flaw stems from incorrect privilege assignment (CWE-266) and allows an attacker with no authentication to escalate privileges on affected WordPress sites. It carries a CVSS v3.1 base score of 8.1 (High).

Technical details

  • Root cause: Incorrect privilege assignment (CWE-266) within the MStore API plugin’s account/role-handling logic.
  • Trigger conditions: No authentication or user interaction is required to trigger the flaw, though the attack complexity is rated High.
  • Attack vector: Network — exploitable remotely against any internet-exposed WordPress site running the vulnerable plugin.
  • Impact: Successful exploitation allows an unauthenticated attacker to escalate privileges, with full impact on confidentiality, integrity, and availability of the affected site.

Affected software

  • MStore API (WordPress plugin) versions ≤ 4.20.0
  • Fixed in version 4.21.0

Severity

  • CVSS v3.1 Base Score: 8.1 (High)
  • Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Mitigation and recommended actions

  • Immediate: Update the MStore API WordPress plugin to version 4.21.0 or later, where the privilege escalation flaw is fixed.
  • If immediate patching is not possible: Restrict or monitor access to the WordPress site’s REST API and admin-facing endpoints, and review user accounts for unauthorized role changes or newly created accounts with elevated privileges.

How IONIX identifies potentially affected assets

IONIX matches the following signals against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.

  • Raw HTTP response body: /wp-content/plugins/mstore-api/

References

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Map your entire attack surface (continously)

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4

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6

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