CVE-2026-112240 in Fluid-Form Extension
Summary
by MITRE • 10/20/2026
The download link for files uploaded through a form relied on a token that could be predicted. The file name in the request was also not verified in a way that resisted guessing. An unauthenticated attacker could use this to access files uploaded by other visitors. In addition, the token was shown in plain text in the text version of the notification email.
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Analysis
by VulDB Data Team • 10/20/2026
The vulnerability described constitutes a critical failure in secure direct object reference implementation and information disclosure mechanisms within a web application's file handling subsystem. At its core, this flaw represents an insecure random value generation issue where the system relies on predictable tokens to govern access to sensitive resources. In modern security architecture, any identifier used to protect private data must be cryptographically strong and unpredictable. The fact that these download tokens could be predicted indicates a reliance on weak pseudo-random number generators or sequential identifiers rather than secure entropy sources such as those defined in cryptographic standards for random value generation. This allows an unauthenticated attacker to systematically guess valid token values, effectively bypassing authentication controls entirely.
The technical flaw is compounded by the lack of server-side validation regarding file names within the request parameters. When a user uploads a file through a form, the application should validate that the requested filename corresponds exactly to what was stored and authorized for upload. The absence of this verification creates an opportunity for path traversal or unauthorized access if combined with predictable tokens. However, even without path traversal vectors, the predictability of the token alone is sufficient to compromise confidentiality. An attacker can iterate through potential token values until a valid one is found, granting them read access to files belonging to other users. This scenario aligns directly with CWE-640, which describes Improper Weakness Management for Password-Based Authentication and Access Control, specifically focusing on the use of weak or predictable identifiers in place of robust authentication mechanisms.
The operational impact of this vulnerability is severe, as it leads to a complete breach of data confidentiality for all users who upload files through the affected form. Since the attacker does not need valid credentials, they can target any file uploaded by any visitor during the window where tokens remain valid or predictable. This could result in the exposure of personally identifiable information, proprietary business documents, medical records, or other sensitive materials depending on the nature of the uploads. The integrity and availability of the system are less directly impacted than confidentiality, but trust in the platform is significantly eroded when users realize their private data can be accessed by strangers through simple enumeration techniques.
A critical aggravating factor in this vulnerability is the exposure of the access token in plain text within notification emails sent to users. This represents a significant information disclosure flaw where sensitive security credentials are transmitted over email channels that may not provide end-to-end encryption or sufficient protection against interception. Email systems often lack robust security controls compared to modern web protocols, making them susceptible to eavesdropping and unauthorized access by third parties. By embedding the token in plain text, the application ensures that even if an attacker cannot guess the token through enumeration, they can still obtain it via email compromise or social engineering attacks targeting recipients. This behavior violates fundamental principles of secure communication and aligns with CWE-209, which covers the generation of error messages containing sensitive information, although here the sensitive data is embedded in user-facing communications rather than just system errors.
To mitigate this vulnerability, developers must immediately replace the predictable token mechanism with a cryptographically strong random identifier generator that meets industry standards for entropy and unpredictability. The length of these tokens should be sufficient to resist brute-force attacks, typically requiring at least 128 bits of randomness. Furthermore, strict validation logic must be implemented on the server side to ensure that every file access request verifies both the validity of the token and its association with the specific user session or upload context. This prevents attackers from using tokens intended for one user to access files belonging to another unless explicitly authorized by a more complex permission model.
Additionally, the application architecture must be revised to prevent the inclusion of sensitive security tokens in plain text within email notifications. If temporary links are necessary for functionality, they should expire rapidly and require additional contextual validation upon use rather than relying solely on the secrecy of the token itself. Implementing short-lived expiration times reduces the window of opportunity for attackers who might intercept emails or guess values. Security headers such as Content-Security-Policy can also be employed to mitigate potential cross-site scripting vectors that could otherwise exfiltrate these tokens from browser sessions. Regular security audits and penetration testing focused on access control flaws are essential to ensure that similar weaknesses do not persist in other parts of the application ecosystem, ensuring compliance with broader frameworks like OWASP Top 10 which categorize broken object level authorization as a top-tier risk.