CVE-2017-20206

CRITICAL EPSS 47.3%
Published Oct 18, 20258mo ago · Modified Jun 17, 20262w ago
9.8 CVSS 3.1
Critical
Find Similar
Published Oct 18, 2025 8mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
9.8
Exploitability
3.9
Impact
5.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
47.3% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-502 Deserialization of Untrusted Data Validation

Affected Products 1

VendorProductVersionRange
wpmudevappointments* ≤2.2.1

References 3

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

Remediation