CVE-2017-20206

Name: CVE-2017-20206
Creator: NVD / NIST
Published: 2025-10-18T04:15:43.243+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 0.67%

Last modified Jun 17, 2026

CVE-2017-20206 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 0.67% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

0.67%

47.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-502

Affected Software

Vendor	Product	Versions
Wpmudev	Appointments	<= 2.2.1

References

https://plugins.trac.wordpress.org/changeset/1733186/appointmentsPatch
https://www.wordfence.com/blog/2017/10/3-zero-day-plugin-vulnerabilities-exploited-wild/Press/Media Coverage, Third Party Advisory
https://www.wordfence.com/threat-intel/vulnerabilities/id/7e8f230e-3f96-4efd-806d-72725b960303?source=cveThird Party Advisory

Timeline

Published: Oct 18, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2017-20206?

How severe is CVE-2017-20206?

CVE-2017-20206 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.67% probability of exploitation in the next 30 days.

How do I fix CVE-2017-20206?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2017-20206?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST