Blocksy <= 2.1.41 - Authenticated (Contributor+) PHP Object Injection via Deserialization of Untrusted Data via 'blocksy_meta' REST API Field

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Summary

CVECVE-2026-8365
StatePUBLISHED
AssignerWordfence
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-09 09:16:31 UTC
Updated2026-06-09 13:33:34 UTC
DescriptionThe 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().

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.009190000 probability, percentile 0.554100000 (date 2026-06-15)

Problem Types: CWE-502 | CWE-502 CWE-502 Deserialization of Untrusted Data

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Creativethemeshq Blocksy affected 2.1.41 semver Not specified

References

ReferenceSourceLinkTags
themes.trac.wordpress.org/browser/blocksy/2.1.41/admin/helpers/validator.php [email protected] themes.trac.wordpress.org
www.wordfence.com/threat-intel/vulnerabilities/id/fd216743-ce8d-4632-9fd1-d6350... [email protected] www.wordfence.com
themes.trac.wordpress.org/browser/blocksy/trunk/inc/classes/db-versioning/utils/db-sear... [email protected] themes.trac.wordpress.org
themes.trac.wordpress.org/browser/blocksy/trunk/admin/helpers/validator.php [email protected] themes.trac.wordpress.org
themes.trac.wordpress.org/browser/blocksy/2.1.35/inc/classes/raii.php [email protected] themes.trac.wordpress.org
themes.trac.wordpress.org/browser/blocksy/2.1.41/inc/classes/raii.php [email protected] themes.trac.wordpress.org
themes.trac.wordpress.org/browser/blocksy/2.1.41/inc/classes/db-versioning/utils/db-sea... [email protected] themes.trac.wordpress.org
themes.trac.wordpress.org/browser/blocksy/trunk/inc/classes/raii.php [email protected] themes.trac.wordpress.org
themes.trac.wordpress.org/browser/blocksy/2.1.35/admin/helpers/validator.php [email protected] themes.trac.wordpress.org
themes.trac.wordpress.org/browser/blocksy/2.1.41/admin/helpers/meta-boxes.php [email protected] themes.trac.wordpress.org
themes.trac.wordpress.org/browser/blocksy/trunk/admin/helpers/meta-boxes.php [email protected] themes.trac.wordpress.org
themes.trac.wordpress.org/browser/blocksy/2.1.35/admin/helpers/meta-boxes.php [email protected] themes.trac.wordpress.org
themes.trac.wordpress.org/browser/blocksy/2.1.35/inc/classes/db-versioning/utils/db-sea... [email protected] themes.trac.wordpress.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Quốc Huy (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-05-12T06:30:57.000ZVendor Notified
CNA2026-06-08T20:11:29.000ZDisclosed
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