9.8

CVE-2017-20206: wordpress appointments Deserialization of Untrusted Data

CVSS: 9.8v3.1CriticalAnalyzed
Published 18-10-2025Last modified 08-04-2026
Open JSON

Vulnerability summary

CVE-2017-20206 is a critical (CVSS 9.8) Deserialization of Untrusted Data vulnerability in wordpress appointments. EPSS estimates a 0.73% chance of exploitation in the next 30 days, higher than 53.5% of scored vulnerabilities. Fixed in 2.2.2.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.73%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 18-10-2025
    PublishedVulnerability first disclosed.
  2. 08-04-2026
    Last modifiedVulnerability information updated.

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 metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.73%

Chance of exploitation in the next 30 days

Percentile

54%

Versus all other CVEs

30-day change

0.00 pp

From 0.73% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.73%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Wordpress1 product
  • appointments< 2.2.2
Wpmudev1 product

2 vendors · 2 products

References

4 links