Description

Authorization bypass through user-controlled key in Azure Cosmos DB allows an authorized attacker to perform spoofing over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.5",
  "pubDate": "2026-09-03T23:17:19.950Z",
  "pubdate": "2026-09-03T23:17:19.950Z",
  "executiveSummary": "This vulnerability involves an authorization bypass mechanism within Azure Cosmos DB, enabling an already authorized attacker to manipulate user-controlled keys.\nThe flaw allows for spoofing attacks over a network, undermining the integrity of access control mechanisms.\nThe vulnerability type is categorized as an authorization bypass, which poses significant security risks to data confidentiality and integrity by circumventing established permission boundaries.\nThe impact is characterized by the potential for unauthorized data access and impersonation of legitimate service entities.\nThe vulnerability affects Azure Cosmos DB instances, requiring the attacker to possess an existing level of authorization to exploit the vulnerability.\nExploitation is conducted over a network, where an attacker leverages specific control over keys to elevate privileges or spoof system identities, thus disrupting trust models in multi-tenant or shared environments.",
  "technicalDetails": "The vulnerability stems from improper validation and handling of user-controlled keys during the authorization process in Azure Cosmos DB. In secure architectures, authorization tokens or keys are expected to be immutable or strictly validated by the service provider against a trusted backend registry. This flaw suggests a failure in the logic where the service relies on or insufficiently sanitizes input parameters representing the authentication or authorization key, allowing a malicious actor to inject or modify these values.\nThe attack flow initiates when an authenticated user, who already possesses access to the environment, interacts with the Azure Cosmos DB service. By manipulating the user-controlled key parameters within the request headers or payload during an API interaction, the attacker can force the application to perform operations outside the scope of their original authorization level.\nSpecifically, the vulnerability allows the attacker to craft a payload that essentially misrepresents their identity or grants them unauthorized permissions by spoofing valid session tokens or cryptographic signatures associated with higher-privilege entities. Because the system fails to correctly map the user's effective identity against the provided key, the authorization check returns a successful status for unauthorized actions.\nThe technical core of the issue resides in the trust boundary between the client-provided key and the server-side authentication engine. By bypassing the intended verification steps, the attacker achieves spoofing, allowing them to intercept or inject data as if they were a different, potentially administrative, user. The network exposure is broad, as this interaction typically occurs over HTTPS protocols where API endpoints are exposed. The post-exploitation impact includes the potential to read, modify, or delete data records within the database that the attacker would not normally have access to, potentially leading to unauthorized data exfiltration or system-wide disruption."
}