CVE-2017-20206
Critical
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.
SeverityCritical
CVSS9.8
Exploit probability—
ProductWpmudev Appointments
PublishedOct 18, 2025
First seenOct 18, 2025
Weakness typeCWE-502Deserialization of untrusted data
How to fix
Sources list no fixed version or patch link for this vulnerability.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| wpmudev appointments | v ≤ 2.2.1 | — |
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