CVE-2026-66634 in Modal Survey Plugin
Summary
by MITRE • 08/18/2026
Subscriber Insecure Direct Object References (IDOR) in Modal Survey <= 2.0.2.2.3 versions.
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Analysis
by VulDB Data Team • 08/18/2026
The vulnerability identified as an insecure direct object reference within the Modal Survey application, specifically affecting versions up to and including 2.0.2.2.3, represents a critical failure in access control mechanisms that allows unauthorized users to manipulate or retrieve data belonging to other subscribers. This class of flaw is formally categorized under CWE-639, which describes situations where an application relies on user-supplied input to identify objects without performing adequate authorization checks. In the context of Modal Survey, this typically manifests when a subscriber interacts with survey-related endpoints that accept identifiers such as survey IDs, submission tokens, or account numbers directly in HTTP requests. Because these parameters are often sequential or predictable, attackers can easily enumerate valid resources by modifying numerical values or alphanumeric strings within request URLs or API payloads to access surveys owned by different users.
From an operational perspective, this vulnerability enables a wide range of malicious activities that compromise the integrity and confidentiality of user data. An attacker with minimal technical expertise can exploit this flaw to view sensitive responses submitted by other subscribers, potentially exposing personal information, professional feedback, or proprietary business insights contained within survey results. Furthermore, depending on the specific implementation details not fully disclosed in the brief description, the vulnerability may also allow for unauthorized modification or deletion of surveys and their associated data if write operations are similarly unprotected. This lack of server-side validation means that the application trusts client-supplied identifiers without verifying whether the requesting user has legitimate ownership or administrative privileges over the targeted resource, leading to a complete breakdown in multi-tenant isolation principles common in SaaS environments.
The security implications extend beyond simple data leakage, impacting compliance with regulatory frameworks such as GDPR and HIPAA if personal health information or personally identifiable information is stored within these surveys. The absence of proper authorization checks aligns closely with the ATT&CK technique T1078, specifically relating to valid accounts being used for unauthorized access, although in this case it is more accurately mapped to privilege escalation through object manipulation rather than credential theft. Attackers can leverage automated tools to rapidly scan for vulnerable endpoints and extract large volumes of data, turning a simple logic error into a significant data breach event that could result in legal liability and reputational damage for the service provider.
Mitigation strategies must focus on implementing robust server-side access control checks at every point where external identifiers are processed. Developers should ensure that all API endpoints and web forms verify that the authenticated user has explicit permission to perform the requested action on the specific resource identified by the input parameter, rather than relying solely on client-side restrictions or session cookies alone. Implementing random, non-sequential identifiers for resources can also reduce the ease of enumeration, although this is a secondary defense compared to strict authorization logic. Additionally, conducting regular code reviews focused on access control patterns and integrating automated static analysis tools that detect CWE-639 violations during the development lifecycle will help prevent similar flaws in future releases. For users currently running affected versions, immediate upgrading to a patched version where these checks are enforced is the primary remediation step until vendor updates become available.