CVE-2026-85671 in QAnything
Summary
by MITRE • 09/04/2026
QAnything 2.0.0 contains an authentication bypass vulnerability in the /api/local_doc_qa/get_file_base64 and /api/local_doc_qa/get_doc endpoints that allows unauthenticated attackers to access any uploaded file or document. Attackers can enumerate file identifiers through unauthenticated endpoints and retrieve base64-encoded files or parsed document chunks without ownership verification to disclose cross-tenant knowledge base content.
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Analysis
by VulDB Data Team • 09/04/2026
The vulnerability identified in QAnything version 2.0.0 represents a critical authentication bypass flaw affecting the local document question answering subsystem. Specifically, the API endpoints /api/local_doc_qa/get_file_base64 and /api/local_doc_qa/get_doc fail to enforce proper access control mechanisms when handling requests for file retrieval and document chunk extraction. This architectural deficiency allows unauthenticated actors to interact with these interfaces without providing valid session tokens or credentials, effectively neutralizing the intended security boundaries of the application. The core technical flaw lies in the server-side logic which processes incoming identifiers for files and documents without verifying that the requesting user owns or has permission to access the specific resource identified by the provided identifier.
This lack of ownership verification enables attackers to perform systematic enumeration attacks against file identifiers. By iterating through sequential or predictable unique identifiers, an attacker can discover valid references to uploaded content within the system. Once a valid identifier is located, the attacker can request the base64-encoded version of any associated file or retrieve parsed document chunks directly from these endpoints. Because there are no checks to ensure that the requester matches the owner of the data, this mechanism facilitates unauthorized access to sensitive information stored in cross-tenant knowledge bases. In multi-tenant deployments where different organizations share infrastructure but expect strict logical isolation, this vulnerability completely undermines tenant separation guarantees.
The operational impact of this vulnerability is severe, leading directly to a comprehensive disclosure of confidential organizational data. Attackers can exfiltrate proprietary documents, internal communications, and other sensitive materials that were uploaded by legitimate users for the purpose of question answering workflows. The ability to retrieve base64-encoded files means attackers can reconstruct original document formats such as PDFs, Word documents, or spreadsheets with high fidelity. Furthermore, access to parsed document chunks allows adversaries to extract specific pieces of information without needing to download entire large files, facilitating efficient data harvesting and potential downstream attacks such as social engineering or competitive intelligence gathering. This constitutes a significant breach of confidentiality across the affected deployment environment.
From a classification perspective, this vulnerability aligns with CWE-287 Improper Authentication, as the system fails to adequately verify identity before granting access to protected resources. It also maps closely to CWE-639 Authorization Bypass Through User-Controlled Key, since the attacker leverages control over input parameters (file/document identifiers) to bypass authorization checks that should rely on user context rather than resource keys alone. In terms of offensive security tactics, this behavior corresponds to ATT&CK technique T1078 Valid Accounts and potentially T1530 Data from Cloud Storage if viewed through the lens of cloud-native data exfiltration patterns, although here it is more accurately described as unauthorized access to application-managed storage via API abuse.
To mitigate this vulnerability, immediate remediation efforts must focus on implementing robust authorization checks at both the endpoint and service layers. Developers should ensure that every request to retrieve files or document chunks includes a validation step that confirms the authenticated user's identity matches the owner of the requested resource. This can be achieved by storing ownership metadata alongside file identifiers in the database and querying this relationship during API execution. Additionally, implementing rate limiting on these endpoints can help mitigate enumeration attacks by slowing down automated identifier guessing attempts. It is also recommended to use non-sequential or cryptographically random unique identifiers for files and documents to increase the difficulty of successful enumeration even if authorization checks are temporarily bypassed. Regular security audits and penetration testing focusing on API access control logic should be conducted to prevent similar flaws in future releases.