Appointments <= 2.2.1 - Unauthenticated PHP Object Injection

Deserialization of Untrusted Data
CVE CVE-2017-20206
CVSS Critical (9.8)
Publicly Published October 2, 2017
Last Updated October 18, 2025
Researcher Matt Barry
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.

References

1 affected software package

Software Type Plugin
Software Slug appointments (view on wordpress.org)
Patched? Yes
Affected Version
  • <= 2.2.2
Patched Version
  • 2.2.2
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