CVE-2017-20206

CRITICAL 9.8

Appointments <= 2.2.1 - Unauthenticated PHP Object Injection

CVSS Score

9.8

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-502
Vendor	wpmudev
Product	appointments
Published	Oct 18, 2025
Last Updated	Apr 8, 2026

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CVSS v3 Breakdown

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

Attack Vector

Attack Complexity

Privileges Required

User Interaction

Scope

Confidentiality

Integrity

Availability

Affected Versions

wpmudev / Appointments

0 < 2.2.2

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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

Credits

Matt Barry