CVE-2026-8365 Deserialization in Blocksy
Authenticated contributors can achieve remote code execution via PHP object injection in the Blocksy WordPress theme during database migration.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-8365?
CVE-2026-8365 is a high-severity unsafe deserialization vulnerability in creativethemeshq Blocksy, published on 9 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The Blocksy theme for WordPress is vulnerable to PHP Object Injection leading to Remote Code Execution via the 'blocksy_meta' REST API field and the V200 database migration in versions up to and including 2.1.35. This is due to insufficient input sanitization in the blocksy_sanitize_post_meta_options() function, which only blocks values containing '<' or '>' and does not prevent serialized PHP object strings from being stored in post meta, combined with the SearchReplacer::run_recursively() function unconditionally deserializing all string values via @unserialize() during migration without restricting allowed classes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject a serialized Blocksy\RaiiPattern object into post meta that, when the V200 migration runs on an upgraded site, is deserialized and triggers RaiiPattern::__destruct(), which executes arbitrary PHP callables via call_user_func().
Weakness: CWE-502
Which versions are affected by CVE-2026-8365?
How do I fix CVE-2026-8365?
No fix has been published for CVE-2026-8365 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-2026-8365 being exploited?
There is no known exploitation of CVE-2026-8365 in the wild and no public exploit code.
Sources
Also known as GHSA-r622-c48h-h6qq.