CVE-2026-88034 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.
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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 instance of an injection-type weakness where user-supplied input is not adequately sanitized before being incorporated into a database command or query structure. In this specific context, the issue arises when a caller supplies a structured file identifier intended to target a specific document within the GridFS bucket. Instead of treating this identifier as a literal value for exact matching, the driver incorrectly interprets certain special elements contained within that input as logical operators or structural components of the query itself. This misinterpretation allows an attacker who can influence the file identifier passed by the application to alter the semantics of the database operation fundamentally.
From a technical perspective, this behavior aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command and more specifically CWE-943 Improper Neutralization of Special Elements in Data Query Logic. The vulnerability stems from the driver's failure to properly escape or validate special characters that have meaning within MongoDB query syntax when they appear inside fields meant for literal matching, such as _id values in GridFS operations. By injecting these elements, an authenticated user can manipulate the underlying BSON structure sent to the database server. This manipulation effectively bypasses intended access controls and data isolation boundaries because the database executes a modified command that differs from what the application developer originally intended.
The operational impact of this vulnerability is severe due to its potential for both unauthorized information disclosure and destructive denial of service. On one hand, an attacker can exploit the query logic flaw to retrieve stored file content beyond the intended target scope. This could lead to the exposure of sensitive data stored in other GridFS buckets or files that were not meant to be accessible by the current user session. On the other hand, the vulnerability allows for more destructive actions where all chunks belonging to a specific GridFS bucket can be removed. Since GridFS relies on multiple chunk documents to reconstruct large files, deleting these chunks renders the associated file content unreadable and effectively destroys data integrity. This capability transforms what might seem like a simple read or write operation into a potent vector for data loss and service disruption.
This type of vulnerability is often categorized under MITRE ATT&CK techniques related to Injection, particularly those involving NoSQL databases where query structure manipulation can lead to privilege escalation or data exfiltration. The attack requires authentication, meaning the threat actor must already have valid credentials within the MongoDB environment. However, once authenticated, the ability to manipulate query logic significantly lowers the barrier for exploitation compared to unauthenticated attacks. It highlights a critical risk in applications that dynamically construct file identifiers from user input without rigorous validation or parameterization strategies appropriate for NoSQL environments.
Mitigation efforts should focus on ensuring that all inputs used as literal values in database queries are strictly validated and treated as such, preventing any interpretation of special characters as query operators. Developers using the MongoDB C++ Driver must ensure they utilize safe APIs that enforce strict typing and escaping mechanisms for identifiers. Upgrading to a patched version of the driver is essential if one exists, as vendors typically address these logic flaws by correcting how input data is serialized into BSON commands. Additionally, implementing least-privilege principles in database access controls can limit the blast radius even if an injection occurs, restricting users from performing bulk deletions or accessing unrelated buckets. Regular security audits of code that interacts with GridFS components are recommended to identify similar patterns where user-controlled data influences query structure directly rather than through parameterized inputs.