CVE-2026-88025 in C# Driver
Summary
by MITRE • 09/10/2026
Improper neutralization of special elements in data query logic in the GridFS component of the MongoDB C# Driver can cause a caller-supplied structured file identifier to be interpreted as a query condition rather than as a literal identifier. An authenticated user who can influence the identifier passed by an affected application may obtain stored file content beyond the intended target or cause all GridFS file chunks in the affected bucket to be removed, rendering stored file content unreadable. The affected rename operation may also rename a stored file other than the intended target.
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Analysis
by VulDB Data Team • 09/10/2026
The vulnerability identified involves improper neutralization of special elements within data query logic, specifically affecting the GridFS component of the MongoDB C# Driver. This flaw represents a classic injection-style issue where user-supplied input is not adequately sanitized before being incorporated into database operations. In this context, the structured file identifier intended to uniquely identify a specific document or chunk in the GridFS system is misinterpreted by the driver as part of a query condition rather than as a literal value. This fundamental misunderstanding of data intent allows an authenticated user who can influence the input passed to the application to manipulate how the database processes requests for file retrieval, modification, or deletion operations.
From a technical perspective, this issue stems from the way the C# driver constructs and executes queries against MongoDB when interacting with GridFS buckets. When a caller supplies a structured identifier that contains special characters or operators typically used in query filters, such as comparison operators or logical conjunctions, the driver fails to escape these elements properly. Consequently, instead of treating the input strictly as an object ID string for lookup purposes, the database engine parses it as a filter expression. This behavior deviates from the expected security boundary where user inputs should be treated as opaque data values rather than executable logic components. The flaw is particularly dangerous because GridFS handles large files by splitting them into chunks stored in separate documents, meaning that an improperly constructed query can inadvertently target multiple records or entire collections depending on how the malicious identifier is structured.
The operational impact of this vulnerability is severe and multifaceted. First, it enables unauthorized data disclosure where an attacker can retrieve file content beyond their intended scope. By crafting a specific input string, an authenticated user might bypass access controls that rely on precise object ID matching, thereby accessing sensitive files stored in the same GridFS bucket or even across different buckets if the query logic allows broader traversal. Second, and more critically, this flaw can lead to data destruction. An attacker could cause all file chunks within a specific GridFS bucket to be removed by injecting deletion operators into what was meant to be an identifier field. This results in the complete loss of stored file content for that bucket, rendering applications unable to read or serve critical assets such as images, documents, or binary data. Additionally, rename operations may affect unintended files, leading to further integrity issues where important resources are moved or overwritten without authorization.
This vulnerability aligns with CWE-94 Improper Control of Generation of Code (Code Injection) and more specifically CWE-78 Improper Neutralization of Special Elements used in an OS Command when viewed through the lens of query construction logic, though it is technically a NoSQL injection variant similar to CWE-943. In terms of the MITRE ATT&CK framework, this behavior corresponds to techniques involving Injection (T1190) and potentially Data Manipulation or Exfiltration depending on whether the attacker reads data or deletes chunks. The attack vector requires authentication, which limits its scope compared to unauthenticated remote code execution vulnerabilities but still poses a significant risk in environments where internal users have varying levels of access privileges.
Mitigation strategies must focus on strict input validation and parameterization practices within the application layer using the C# driver. Developers should ensure that all identifiers passed to GridFS operations are validated against expected formats, such as standard hexadecimal object ID strings, before being used in queries. Utilizing strongly typed parameters provided by modern database drivers rather than concatenating raw user input into query structures is essential. Furthermore, implementing least-privilege principles for the application's database account can limit the blast radius if an injection occurs; restricting delete permissions on GridFS collections would prevent chunk removal even if the identifier manipulation succeeds. Regular security audits and static analysis tools configured to detect potential NoSQL injection patterns in C# codebases are also recommended to identify similar flaws before deployment.