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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.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-8365 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-8365

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-8365 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-8365

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.