CVE-2026-106077 in Backup for Microsoft 365
Summary
by MITRE • 10/27/2026
A vulnerability allowing a user with the Veeam Backup for Microsoft 365 Administrator role to read arbitrary files on the backup server with LocalSystem privileges.
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Analysis
by VulDB Data Team • 10/27/2026
The identified security flaw represents a critical privilege escalation vector within the Veeam Backup for Microsoft 365 infrastructure, specifically targeting administrators who hold the designated administrator role. This vulnerability stems from an improper access control mechanism that fails to adequately restrict file system operations based on the principle of least privilege. While the administrative interface is intended for managing backup policies and configurations rather than direct server interaction, the underlying implementation allows authenticated users with this specific role to execute commands or invoke functions that result in reading arbitrary files directly from the operating system's file structure. This discrepancy between the expected functional scope of an administrator account and its actual permissions creates a significant security gap that can be exploited by malicious insiders or attackers who have compromised administrative credentials.
From a technical perspective, this flaw is classified under CWE-269, which denotes Improper Privilege Management, as it involves a user possessing elevated privileges being able to perform actions beyond their intended scope without requiring further authentication or authorization checks. The vulnerability effectively bypasses standard security boundaries by leveraging the LocalSystem account context in which many backup services operate. By exploiting this weakness, an attacker can read sensitive configuration files, credential stores, database connection strings, and potentially other proprietary data stored on the server. This capability undermines the integrity of the entire backup infrastructure because it allows for the exfiltration of secrets that are critical to maintaining secure operations within a Microsoft 365 environment.
The operational impact of this vulnerability is severe due to the high level of access granted by LocalSystem privileges, which typically possess unrestricted control over the local system. An adversary leveraging this flaw could extract encryption keys used for backup protection, thereby rendering encrypted backups accessible and compromising data confidentiality at rest. Furthermore, the ability to read arbitrary files may facilitate further attacks such as credential harvesting or lateral movement within the network if sensitive configuration details are exposed. This scenario aligns with ATT&CK technique T1005, which describes Data from Local System Retrieval, indicating that the vulnerability enables an attacker to gather valuable information directly from the host system without needing advanced exploitation techniques beyond initial access through administrative credentials.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Veeam has released patches addressing this specific issue, so applying the latest updates is the primary corrective action required for affected systems. In addition to patching, organizations should enforce strict role-based access control by ensuring that only essential personnel have administrator privileges within the backup solution. Implementing multi-factor authentication for administrative accounts adds a crucial layer of defense against credential theft or misuse. Regular auditing of administrative activities and monitoring for unusual file system access patterns can also help detect potential exploitation attempts early. Security teams should review their current permission assignments to ensure they align with industry best practices, minimizing the attack surface associated with high-privilege roles in critical backup infrastructure components.