CVE-2017-20206

critical · 9.8

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.

9.8

CVSS

0.7%

EPSS (exploit prob.)

53rd

EPSS percentile

2025-10-18

Published

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaknesses

CWE-502

Affected products

Vendor	Product	Affected versions
wpmudev	appointments	<= 2.2.1

Check a specific version with /api/v1/cve/match.

References

https://plugins.trac.wordpress.org/changeset/1733186/appointments
https://www.wordfence.com/blog/2017/10/3-zero-day-plugin-vulnerabilities-exploited-wild/
https://www.wordfence.com/threat-intel/vulnerabilities/id/7e8f230e-3f96-4efd-806d-72725b960303?source=cve

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2017-20206