CVE-2017-20206 Appointments <= 2.2.1 - Unauthenticated PHP Object Injection
Unauthenticated attackers can inject PHP objects via a cookie to execute code and create backdoors in the Appointments WordPress plugin.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2017-20206?
CVE-2017-20206 is a critical unsafe deserialization vulnerability in wpmudev Appointments, published on 18 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-502
Which versions are affected by CVE-2017-20206?
It affects 1 product.
Products include Wpmudev Appointments.
How do I fix CVE-2017-20206?
No fix has been published for CVE-2017-20206 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2017-20206 being exploited?
There is no known exploitation of CVE-2017-20206 in the wild and no public exploit code.
Sources
Also known as GHSA-7mpm-gf56-q8wv.