CVE-2026-66803 in Azure Cosmos DB
Summary
by MITRE • 07/31/2026
Improper access control in Azure Cosmos DB allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 07/31/2026
Azure Cosmos DB implements a robust security model that includes multiple layers of protection for data and services, yet improper access control configurations can create significant vulnerabilities that expose systems to remote code execution attacks. This weakness typically arises from misconfigured permission settings, inadequate role-based access controls, or flawed authentication mechanisms within the database service. The vulnerability stems from the fundamental principle that access control must be properly enforced at all levels of the system architecture, where insufficient restrictions allow unauthorized entities to bypass normal security boundaries and gain elevated privileges.
The technical flaw manifests when default configurations are not properly secured, when least privilege principles are ignored during setup, or when administrative credentials are compromised through credential theft attacks. Attackers can exploit these misconfigurations by leveraging network-based access points to manipulate database permissions, inject malicious commands, or directly execute code on the underlying infrastructure. This typically occurs through manipulation of API keys, service endpoints, or connection strings that lack proper encryption or authentication controls. The vulnerability aligns with CWE-284 which describes improper access control and represents a critical weakness in authorization mechanisms that allows unauthorized users to perform privileged operations.
When exploited, this vulnerability can have severe operational impacts including complete system compromise, data exfiltration, service disruption, and potential lateral movement within the network infrastructure. The attack surface expands significantly when Cosmos DB instances are exposed to untrusted networks without proper firewall rules or when administrative accounts lack multi-factor authentication. The remote code execution capability allows attackers to establish persistent access, deploy malware, or conduct advanced persistent threat operations that can remain undetected for extended periods.
Mitigation strategies must focus on implementing strict access control policies that follow the principle of least privilege and employ defense-in-depth approaches. Organizations should configure Cosmos DB with proper firewall rules, implement network security groups, enable secure communication protocols such as TLS 1.3, and regularly audit access permissions through automated monitoring systems. The implementation should include multi-factor authentication for administrative accounts, regular credential rotation, and comprehensive logging of all access attempts. Security controls should align with industry standards including the NIST Cybersecurity Framework and ISO 27001 requirements for access management, while also addressing ATT&CK techniques related to privilege escalation and persistence mechanisms that attackers might employ through such vulnerabilities. Regular security assessments and penetration testing should be conducted to identify misconfigurations before they can be exploited by malicious actors.