PatchSiren cyber security CVE debrief
CVE-2026-8365 creativethemeshq CVE debrief
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().
- Vendor
- creativethemeshq
- Product
- Blocksy
- CVSS
- HIGH 8.8
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-06-09
- Original CVE updated
- 2026-06-09
- Advisory published
- 2026-06-09
- Advisory updated
- 2026-06-09
Who should care
Users of the Blocksy theme for WordPress, particularly those with contributor-level access and above, should be aware of this vulnerability and take steps to mitigate it.
Technical summary
The vulnerability has a CVSS score of 8.8 and is classified as HIGH severity. It is caused by a combination of insufficient input sanitization and unconditional deserialization of string values during database migration.
Defensive priority
high
Recommended defensive actions
- Update the Blocksy theme to a version that fixes the vulnerability.
- Restrict access to the 'blocksy_meta' REST API field.
- Implement additional input sanitization and validation.
Evidence notes
Evidence for this vulnerability comes from the NVD and Wordfence security research.
Official resources
CVE-2026-8365 was published on 2026-06-09T09:16:31.013Z and modified on 2026-06-09T13:33:34.393Z.