CVE-2026-86194 in Form Plugin
Summary
by MITRE • 09/05/2026
Grav Form Plugin before 9.1.22 fails to verify page authorization when resolving forms by name across pages, allowing anonymous visitors to execute form actions defined on login-restricted or unpublished pages. Attackers can POST to any public page with a restricted form's name to trigger save, upload, email, or call actions without authentication.
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Analysis
by VulDB Data Team • 09/05/2026
The vulnerability identified in Grav Form Plugin versions prior to 9.1.22 represents a critical failure in access control logic within the plugin’s form resolution mechanism. The core technical flaw lies in how the system locates and processes forms when they are referenced by name across different pages. Instead of validating whether the current user has permission to view or interact with the specific page where the form is defined, the plugin resolves the form based solely on its unique identifier within the site’s content structure. This architectural oversight effectively decouples the execution context from the security boundaries established at the page level, creating a significant authorization bypass that undermines the intended confidentiality and integrity of restricted content.
From an operational perspective, this flaw allows unauthenticated or anonymous visitors to trigger actions associated with forms located on login-restricted or unpublished pages. By constructing specific HTTP POST requests directed at any publicly accessible URL within the Grav installation, attackers can supply the name parameter corresponding to a protected form. The plugin then locates that form definition and executes its configured actions without performing any authentication checks against the user’s session or role permissions. This capability transforms what should be private administrative or member-only functionalities into public-facing endpoints, exposing sensitive data processing workflows to external actors who lack legitimate access rights.
The impact of this vulnerability is severe, particularly for websites that rely on Grav Form Plugin features such as file uploads, email notifications, and custom action calls within restricted areas. Attackers can exploit this flaw to upload malicious files directly to the server’s filesystem if the form includes a file upload field with insufficient validation, potentially leading to remote code execution or web shell deployment. Furthermore, unauthorized users can trigger mass email dispatches using templates intended for internal communication only, which may result in spamming, phishing campaigns originating from the victim’s domain reputation, or exposure of recipient lists contained within those emails. Additionally, any custom actions defined via plugins that interact with external APIs or databases could be abused to perform unintended operations, such as modifying database records or invoking sensitive administrative functions without proper authorization checks.
This vulnerability aligns closely with CWE-284 Improper Access Control and CWE-359 Exposure of Private Information to an Unauthorized Actor under the Common Weakness Enumeration standard. In terms of offensive security tactics, it maps directly to ATT&CK technique T1078 Valid Accounts when considering how attackers might leverage valid but unintended access paths, although in this specific case, no account is required at all due to the complete bypass of authentication logic for form resolution. The exploitation vector falls under T1190 Exploit Public-Facing Application as it targets a web application component exposed to the internet with insufficient input validation regarding user context and permissions.
To mitigate this risk, administrators must upgrade the Grav Form Plugin to version 9.1.22 or later immediately upon availability, as these versions include patches that enforce proper authorization checks during form resolution regardless of how the form is referenced. Until an update can be applied, site operators should consider implementing web application firewall rules that monitor for anomalous POST requests containing specific form name parameters on public pages, although this serves only as a temporary compensating control rather than a definitive fix. It is also advisable to review all forms configured with sensitive actions such as file uploads or email dispatches and ensure they are placed exclusively on publicly intended pages if possible, while avoiding the use of restricted page contexts for any form that handles critical data or triggers external integrations. Regular auditing of plugin configurations against current security best practices will help prevent similar authorization bypass vulnerabilities in future deployments.