CVE-2026-19677 in Forms
Summary
by MITRE • 10/23/2026
An authentication bypass vulnerability in the public onPhase/ frevvo registration form version 11.0.14 allows an unauthenticated remote attacker to authenticate as an arbitrary tenant user, obtain TenantAdmin and Designer privileges, and execute arbitrary operating system commands via manipulation of registration parameters containing a valid tenant name and existing user identifier.
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Analysis
by VulDB Data Team • 10/23/2026
The vulnerability identified in frevvo version 11.0.14 represents a critical authentication bypass flaw within the public onPhase registration form functionality. This security defect allows an unauthenticated remote attacker to circumvent standard access controls by manipulating specific input parameters during the tenant user registration process. The core technical issue stems from insufficient validation of the relationship between the provided tenant name and the existing user identifier supplied in the request payload. By crafting a malicious HTTP request that includes a valid tenant name alongside an existing, legitimate user identifier within the registration form fields, an attacker can trick the application into treating this input as a standard new account creation or password reset flow. The system fails to adequately verify whether the requesting entity has authorized permission to associate with the specified identity, thereby allowing the injection of administrative privileges into unauthorized accounts.
Upon successful exploitation, the immediate operational impact is severe privilege escalation. An attacker who successfully leverages this flaw can authenticate as an arbitrary tenant user and subsequently elevate their session rights to obtain TenantAdmin and Designer roles. These elevated permissions grant extensive control over the application environment, including the ability to manage users, configure system settings, and design complex workflows without restriction. This level of access fundamentally compromises the integrity and confidentiality of the entire multi-tenant SaaS platform, as the attacker gains a trusted foothold within the administrative boundary of the targeted tenant organization.
The most critical consequence of this privilege escalation is the capability to execute arbitrary operating system commands on the underlying server infrastructure. With TenantAdmin or Designer privileges, an attacker can exploit built-in features such as custom script execution, workflow automation rules, or integration endpoints that allow for code injection. By embedding malicious payloads within these configurable elements, the attacker achieves remote code execution (RCE) with the same level of privilege as the application process itself. This transforms a simple authentication bypass into a full system compromise, enabling data exfiltration, lateral movement to other systems on the network, and persistent backdoor installation.
From an industry standard perspective, this vulnerability aligns closely with CWE-287, which describes Improper Authentication, specifically involving the failure to verify identity before granting elevated privileges. Furthermore, the exploitation path relates to CWE-613, Insufficient Session Expiration, as it involves hijacking or forging session contexts through parameter manipulation. In terms of MITRE ATT&CK mapping, this flaw facilitates Initial Access via Valid Accounts and Privilege Escalation techniques such as T1078 (Valid Accounts) and potentially Command and Control mechanisms if the RCE is leveraged for persistent connectivity. The attack vector also reflects aspects of CWE-94, Improper Control of Generation of Code, due to the subsequent OS command execution capability derived from misconfigured application features accessible only after bypassing authentication.
Mitigation strategies must prioritize immediate patching to version 11.0.15 or later where this logic flaw has been corrected by implementing strict validation checks on tenant-user associations during registration flows. Security administrators should also enforce role-based access control (RBAC) principles that limit the exposure of administrative functions, ensuring that Designer and TenantAdmin capabilities are not accessible through public-facing forms without rigorous multi-factor authentication and explicit authorization checks. Additionally, deploying a Web Application Firewall with rules targeting parameter tampering in registration endpoints can provide an additional layer of defense against exploitation attempts while patches are being applied to production environments.