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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
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
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.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
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: 2 proofs of concept on GitHub.
Sources
Also known as GHSA-4q25-cq4p-f83q.