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CVE-2017-20206

CRITICAL 9.8 CVSS 3.1
Published
October 18, 2025
Last modified
June 17, 2026
NVD status
Analyzed
Reported by
security@wordfence.com
Weakness
CWE-502
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Description

The Appointments plugin for WordPress is vulnerable to PHP Object Injection in versions up to, and including, 2.2.1 via deserialization of untrusted input from the `wpmudev_appointments` cookie. This allows unauthenticated attackers to inject a PHP Object. Attackers were actively exploiting this vulnerability with the WP_Theme() class to create backdoors.

Affected WordPress components

A confirmed match is backed by the plugin or theme slug. A possible match is based on the product name only and should be verified.

Affected products and versions

  • wpmudev Appointments — Before 2.2.2
  • wpmudev appointments — Up to and including 2.2.1

References

  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/changeset/1733186/appointments Patch
  • www.wordfence.com https://www.wordfence.com/blog/2017/10/3-zero-day-plugin-vulnerabilities-exploited-wild/ Press/Media Coverage, Third Party Advisory
  • www.wordfence.com https://www.wordfence.com/threat-intel/vulnerabilities/id/7e8f230e-3f96-4efd-806d-72725b960303?source=cve Third Party Advisory
  • nvd.nist.gov Official NVD record