CVE-2026-49159 in Graph
Summary
by MITRE • 07/24/2026
Exposure of sensitive information to an unauthorized actor in Microsoft Graph allows an authorized attacker to disclose information over a network.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/24/2026
This vulnerability represents a critical information disclosure flaw within Microsoft Graph API that enables authenticated attackers to access sensitive data through network communications. The issue stems from inadequate access controls and authorization mechanisms within the graph service, allowing malicious actors who have already established legitimate credentials to escalate their privileges and extract confidential information from the system. The vulnerability operates at the application layer where proper authentication tokens are accepted but insufficient authorization checks are performed, creating a pathway for unauthorized data exposure. This flaw directly violates fundamental security principles of least privilege and principle of least authority, as users can access resources beyond their intended scope of permissions.
The technical implementation of this vulnerability involves Microsoft Graph's API endpoint handling where authentication is validated but authorization boundaries are not properly enforced. Attackers can leverage valid session tokens or access credentials to make requests that should be restricted based on user roles, tenant permissions, or data sensitivity classifications. The flaw typically manifests when the system fails to validate whether a requesting entity has appropriate clearance levels for specific data sets or resource types within the graph infrastructure. This allows attackers to enumerate and retrieve information such as user profiles, directory data, email contents, file metadata, and other sensitive organizational information that should remain protected under normal security controls.
The operational impact of this vulnerability extends beyond simple data theft to encompass significant business and compliance risks for affected organizations. Organizations using Microsoft Graph services experience potential exposure of personally identifiable information, corporate intellectual property, and confidential business data that could be exploited for financial gain, competitive advantage, or further attack vectors. The network-based nature of the exploit means that attackers can remotely access this information without requiring physical presence or complex local system compromise techniques. This makes the vulnerability particularly dangerous as it can be exploited from anywhere with network connectivity and appropriate credentials, potentially enabling large-scale data breaches affecting thousands of users and sensitive organizational assets.
Mitigation strategies for this vulnerability require implementing robust authorization controls within Microsoft Graph API configurations, including enhanced role-based access control mechanisms, proper data classification systems, and comprehensive audit logging. Organizations should deploy strict API endpoint validation procedures that enforce granular permissions for each request, ensuring that access tokens are validated against comprehensive permission matrices rather than simple authentication states. Security teams must implement continuous monitoring of API access patterns to detect anomalous behavior indicative of unauthorized information extraction attempts. Additionally, regular security assessments and penetration testing should be conducted to identify potential authorization bypass opportunities. The remediation process involves configuring Microsoft Graph with appropriate access control policies, enabling detailed logging of all API interactions, and establishing automated alerting mechanisms for suspicious data access patterns. Organizations should also consider implementing zero-trust network architectures that continuously validate access requests regardless of the initial authentication status. This vulnerability aligns with CWE-284 which addresses improper access control issues, and maps to ATT&CK technique T1078 for valid accounts and T1567 for exfiltration over web services.