The vulnerability chain, codenamed 'CosmosEscape' by Wiz, affected Azure Cosmos DB's Gremlin API. The exploit begins with an attacker controlling a Gremlin database account. Azure Cosmos DB's custom Gremlin engine translates Gremlin queries into .NET code and executes them inside a restricted sandbox environment. The sandbox failed to account for .NET reflection, allowing researchers to build file-read and file-write primitives and ultimately achieve arbitrary code execution. Code execution landed on the DB Gateway, a component running customer queries on multi-tenant Azure Service Fabric clusters. From the DB Gateway, attackers could access a platform-wide signing secret dubbed the 'Cosmos Master Key.' This master key could retrieve the primary account key for any Cosmos DB account across all tenants, regions, and APIs (SQL, MongoDB, Cassandra, and Gremlin). The same secret also provided access to a regional 'Config Store' — a directory containing Cosmos DB account names, subscription and tenant identifiers, network settings, and tags — enabling targeted attacks against specific organizations. The exploit could also reach private and network-isolated accounts since the compromised gateway enforced network boundaries from inside the service. Write access to the Config Store also suggested network settings could potentially be modified. Data stored in Cosmos DB including Microsoft Teams messages and Microsoft Copilot conversation histories were potentially accessible. The vulnerability was reported to Microsoft in November 2025; the Gremlin entry point was blocked within 48 hours. The full long-term fix and elimination of the platform-wide key was completed across all regions in July 2026. The complete exploit chain is to be presented at Black Hat USA on August 6.