# CVE-2026-78006: The Events Calendar <= 6.17.4 - Unauthenticated PHP Object Injection to Remote Code Execution

> Unauthenticated attackers can achieve remote code execution via PHP object injection in The Events Calendar plugin when comments are enabled.

- **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:** 12 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** GHSA-4q25-cq4p-f83q

## What is CVE-2026-78006?

CVE-2026-78006 is a critical unsafe deserialization vulnerability in stellarwp The Events Calendar, published on 12 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The The Events Calendar plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 6.17.4 via the is_safe_widget_instance function. This is due to insufficient protection in is_safe_widget_instance, which can be bypassed because PHP fires magic methods during its pre-parse, combined with enable_rendering_widget_copied() forging a valid wp_hash integrity attribute before unserialize() is reached. This makes it possible for unauthenticated attackers to execute code on the server. This is exploitable without authentication or approval because the plugin's V2 single-event template runs do_blocks() over buffered comment HTML, and WordPress returns a moderation-hash URL that allows an unauthenticated commenter to immediately view their own pending comment, delivering the injected block markup to the vulnerable code path before any moderation occurs. This does require comments to be enabled and visible on events.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-78006?


## How do I fix CVE-2026-78006?

No fix has been published for CVE-2026-78006 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-78006 being exploited?

There is no known exploitation of CVE-2026-78006 in the wild and no public exploit code.

Public exploit code:

- POC for CVE-2026-78006 The Events Calendar <= 6.17.4 - Unauthenticated PHP Object Injection to Remote Code Execution (github_poc): https://github.com/DeadExpl0it/CVE-2026-78006-POC
- The Events Calendar Wordpress Plugin Mass Exploit CVE-2026-78006 & CVE-2026-78159 (github_poc): https://github.com/antid00t/CVE-2026-78006-CVE-2026-78159

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-78006 and fix it if it is affected.

What it is: CVE-2026-78006 is a critical unsafe deserialization vulnerability in stellarwp The Events Calendar, published on 12 Sep 2026. 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-2026-78006 in the wild and no public exploit code.

Affected product: stellarwp The Events Calendar. 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-2026-78006/ (Markdown: https://insights.sbomify.com/CVE-2026-78006/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-78006
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-78006
- OSV: https://osv.dev/vulnerability/CVE-2026-78006

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-78006/
Summaries are generated and may contain mistakes; the official description above is the record.