EUVD-2026-66946
GHSA-j565-hhqc-8rx3
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessIdentify site running Hash Form ≤1.4.1
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DeliverySend crafted request with serialized PHP object
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ExploitPlugin deserializes untrusted input
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ExecutionGadget chain magic methods invoked
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ImpactAchieve code execution or data compromise
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A08:2025 - Software or Data Integrity Failures
ASVS 5.0
V1 - Encoding and Sanitization Safe deserialization, type allowlists
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Initial Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires that the target runs Hash Form version 1.4.1 or earlier and that an attacker can reach the plugin's input-processing endpoint over the network - no authentication and no user interaction are needed (PR:N/UI:N). The practical limiting factor is that PHP object injection only achieves meaningful impact when a usable gadget chain exists in the deployed WordPress stack (core, Hash Form, or another active plugin/theme); on a site with no reachable gadget, impact may be reduced. No non-default configuration is stated as required in the source data. |
| Impact | The signals point to a genuinely high-priority issue rather than an inflated CVSS: the vector is fully remote and unauthenticated (AV:N/AC:L/PR:N/UI:N) with high impact across confidentiality, integrity, and availability, and the vulnerability class (PHP object injection) is a well-understood, reliably weaponizable primitive on WordPress. That said, real-world exploitability hinges on the presence of a usable gadget chain in the target environment, which introduces variability the CVSS score does not capture. EPSS was not provided, there is no KEV listing, and no public POC is identified, so exploitation is currently theoretical-but-plausible rather than confirmed in the wild; any operator running an affected version should treat it as urgent and patch promptly. The absence of EPSS and KEV data means prioritization rests primarily on the CVSS vector and the intrinsic reliability of the deserialization class. |
| Exploit ScenarioDerived | An attacker sends a crafted, unauthenticated HTTP request to a Hash Form endpoint with a parameter containing a serialized PHP object payload. The plugin deserializes the input, instantiating an attacker-chosen object whose magic methods trigger a gadget chain in WordPress or another installed component, leading to actions such as arbitrary file write or code execution. No public POC is identified at time of analysis, but the low attack complexity and lack of authentication make reliable exploitation likely once a suitable gadget chain is identified. |
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Alert meAnalysisAIv1 – Aug 27, 2026
PHP Object Injection in the Hash Form WordPress plugin (versions 1.4.1 and earlier) lets remote, unauthenticated attackers inject crafted serialized objects that are deserialized by the plugin, enabling code execution, data tampering, or site compromise depending on available gadget chains. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N) rates it 9.8 Critical with no authentication required. There is no public exploit identified at time of analysis and it is not listed in CISA KEV.
RemediationAI
No vendor-released patch version is identified in the provided data; the input confirms only that versions up to and including 1.4.1 are vulnerable. Administrators should check the Patchstack advisory (https://patchstack.com/database/wordpress/plugin/hash-form/vulnerability/wordpress-hash-form-plugin-1-4-1-php-object-injection-vulnerability) and the WordPress plugin page for a release newer than 1.4.1 and upgrade as soon as one is available. Until a confirmed fixed version is deployed, the strongest compensating control is to deactivate and remove the Hash Form plugin, which eliminates the vulnerable code path at the cost of losing all forms it powers; where removal is not feasible, restrict access to the plugin's form-submission and AJAX endpoints via a WAF rule or web-server access control that blocks or inspects serialized-object payloads (values containing patterns like 'O:' or 'a:' in relevant parameters), accepting the risk of false positives on legitimate submissions and that WAF signatures may be bypassable.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The affected component is Hash Form, a drag-and-drop form-builder plugin for WordPress published by hashthemes (CPE cpe:2.3:a:hashthemes:hash_form). The root cause is CWE-502, Deserialization of Untrusted Data: the plugin passes attacker-controllable input into a PHP deserialization routine (typically unserialize()) without validation. PHP object injection becomes exploitable when the deserialized object interacts with a 'gadget' - a class with magic methods such as __wakeup(), __destruct(), or __toString() - present in WordPress core, the plugin itself, or another installed plugin/theme, which the attacker chains to achieve file operations, SQL manipulation, or arbitrary code execution.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Unauthenticated remote deserialization with low complexity (AV:N/AC:L/PR:N/UI:N); PHP object injection can yield code execution, so C/I/A all High.
Primary rating from Vendor (Patchstack).
CVSS VectorVendor: Patchstack
DescriptionCVE.org
Unauthenticated PHP Object Injection in Hash Form <= 1.4.1 versions.
Articles & Coverage 1
Executive ViewAI
The Hash Form WordPress plugin versions 1.4.1 and earlier contain a critical PHP Object Injection vulnerability that allows unauthenticated remote attackers to execute arbitrary code on affected sites. Any organization using this plugin faces immediate risk of complete site compromise, malware installation, and data theft without requiring valid login credentials. Immediate deactivation and removal is mandatory until a vendor patch is released.
No vendor-released patch identified at time of analysis. Interim mitigations: (1) complete removal of the Hash Form plugin from all WordPress installations; (2) Web Application Firewall rules denying requests to the vulnerable plugin directory; (3) daily security scanning and log monitoring for indicators of unauthorized code execution or successful exploitation attempts.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Insecure deserialization occurs when an application converts serialized data (a stream of bytes representing an object's state) back into a living object without proper validation.
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