Description

A weakness in the MongoDB C++ Driver's handling of caller-supplied namespace identifiers allows special characters embedded in those identifiers. An application that builds a namespace identifier from untrusted input without validating it may therefore have its operation directed at a different target than intended. This can result in limited unauthorized read and write access to data belonging to another logical tenant of the affected application.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.1",
  "pubDate": "2026-08-27T20:18:50.493Z",
  "pubdate": "2026-08-27T20:18:50.493Z",
  "executiveSummary": "This vulnerability involves an improper neutralization of special elements within namespace identifiers in the MongoDB C++ Driver. The flaw arises when the driver processes caller-supplied strings used to construct database or collection namespaces without sufficient sanitization or validation.\nThe vulnerability allows an attacker to manipulate the target namespace, effectively redirecting database operations to unintended collections or databases. By injecting control characters or delimiters, an adversary can bypass application-level isolation logic, leading to unauthorized read or write access to data partitions or logical tenants that the application was never intended to access.\nThis issue represents a significant security risk for multi-tenant applications leveraging the MongoDB C++ Driver, where strict data segmentation is required. Exploitation does not necessarily require direct network access to the MongoDB cluster, but rather hinges on the application's ingestion of untrusted input that is subsequently passed to the driver's namespace handling routines.\nThe primary risk implication is a breach of data confidentiality and integrity, as attackers can exfiltrate sensitive information from other tenants or inject malicious data into unauthorized namespaces. Organizations relying on the MongoDB C++ Driver must ensure that all namespace identifiers are rigorously validated against an allowlist before being processed by the driver.",
  "technicalDetails": "The root cause of this vulnerability is the lack of strict input sanitization within the MongoDB C++ Driver when handling namespace strings. In MongoDB, a namespace is typically formatted as 'database.collection'. If the driver fails to properly escape or validate the components of this string, an attacker can supply specially crafted inputs containing delimiters such as '.' or other control characters.\nWhen an application constructs a namespace dynamically using unsanitized user input, the MongoDB C++ Driver may interpret the injected characters as structural components of the namespace identifier rather than literal data. For example, if an application constructs a query for a user-owned collection by concatenating a base prefix with a user-supplied identifier, an attacker providing a payload containing namespace separators can navigate the directory structure of the MongoDB deployment.\nThe attack flow proceeds as follows: First, the attacker identifies an application entry point that accepts user input which is subsequently utilized to define the target database or collection in a MongoDB operation. Second, the attacker crafts a malicious string containing namespace delimiters designed to escape the expected logical scope. Third, the application passes this unvalidated string directly to the driver's API methods. Finally, the driver interprets the malicious string as a valid, albeit different, namespace, allowing the attacker to perform authorized CRUD operations on arbitrary namespaces within the cluster.\nThe vulnerability is primarily located within the driver's internal string parsing and namespace resolution logic. Because the driver treats the identifier as a trusted path, it performs the requested operation (e.g., find, update, insert) against the unintended target. If the MongoDB service account possesses broad permissions, the impact is magnified, as the attacker may inadvertently interact with administrative or system collections, potentially leading to unauthorized data exposure or modification.\nThis flaw effectively facilitates a form of injection attack similar to directory traversal but specialized for the MongoDB driver's namespace handling. Successful exploitation results in the circumvention of application-defined access control lists (ACLs) and logical tenant isolation, granting the attacker the ability to pivot between isolated data environments hosted on the same database server."
}