# CVE-2017-20206: Appointments <= 2.2.1 - Unauthenticated PHP Object Injection

> Unauthenticated attackers can inject PHP objects via a cookie to execute code and create backdoors in the Appointments WordPress plugin.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Oct 2025
- **Updated:** 8 Apr 2026
- **Also known as:** GHSA-7mpm-gf56-q8wv

## What is CVE-2017-20206?

CVE-2017-20206 is a critical unsafe deserialization vulnerability in wpmudev Appointments, published on 18 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2017-20206?

It affects 1 product.


Products: Wpmudev Appointments.

## How do I fix CVE-2017-20206?

No fix has been published for CVE-2017-20206 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-20206 being exploited?

There is no known exploitation of CVE-2017-20206 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-20206 and fix it if it is affected.

What it is: CVE-2017-20206 is a critical unsafe deserialization vulnerability in wpmudev Appointments, published on 18 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2017-20206 in the wild and no public exploit code.

Affected product: wpmudev Appointments. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2017-20206/ (Markdown: https://insights.sbomify.com/CVE-2017-20206/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-20206
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-20206
- OSV: https://osv.dev/vulnerability/CVE-2017-20206

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From sbomify Insights: https://insights.sbomify.com/CVE-2017-20206/
Summaries are generated and may contain mistakes; the official description above is the record.