CVE-2017-20206
CRITICAL EXPLOITEDAppointments plugin for WordPress <=2.2.1 - Code Injection
Title source: llmExploitation Summary
CVE-2017-20206 has been observed exploited in the wild (reported by VulnCheck KEV).
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 (3)
Core 3
Core References
Press/Media Coverage, Third Party Advisory
https://www.wordfence.com/blog/2017/10/3-zero-day-plugin-vulnerabilities-exploited-wild/
Scores
CVSS v3
9.8
EPSS
0.0067
EPSS Percentile
47.3%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
yes
Technical Impact
total
Details
VulnCheck KEV
2017-10-02
CWE
CWE-502
Status
published
Products (2)
wpmudev/appointments
< 2.2.1
wpmudev/Appointments
< 2.2.2
Published
Oct 18, 2025
Tracked Since
Feb 18, 2026