CVE-2017-20206: The Appointments plugin for WordPress is vulnerable to PHP Object Injection in versions up to, and including,

Q: How do I fix CVE-2017-20206?

appointments: upgrade to newer than 2.2.1. Exact commands for each OS are on this page.

Q: Is CVE-2017-20206 being exploited?

CVE-2017-20206 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2017-20206 affect?

CVE-2017-20206 affects appointments. Severity is critical (CVSS 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 inje

Q: How urgent is CVE-2017-20206?

Priority 53/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2017-20206 is a critical-severity flaw (CVSS 9.8) affecting appointments. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-502
Published	2025-10-18
Last modified	2026-06-17

Publisher (CNA): Wordfence · Vendor: wpmudev

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-10-18 04:15 UTCPublished CVE record published
2026-06-17 01:15 UTCUpdated Record last modified

wpmudev appointments UPGRADE

Affected: <= 2.2.1

Fixed in: newer than 2.2.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy appointments || rpm -q appointments || appointments --version

2. UPGRADE to newer than 2.2.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade appointments

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade appointments

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2017-20206?

appointments: upgrade to newer than 2.2.1. Exact commands for each OS are on this page.

Is CVE-2017-20206 being exploited?

CVE-2017-20206 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2017-20206 affect?

CVE-2017-20206 affects appointments. Severity is critical (CVSS 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 inje

How urgent is CVE-2017-20206?

Priority 53/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

WordPress vulnerabilities · PHP vulnerabilities

References

← Back to latest CVEs