CVE-2026-16053 in M365 Manager Plus
Summary
by MITRE • 08/11/2026
Zohocorp ManageEngine M365 Manager Plus and M365 Security Plus versions below 4820 are affected to Authenticated Path Traversal vulnerability in Exchange Online backup module.
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Analysis
by VulDB Data Team • 08/11/2026
The vulnerability under discussion represents a critical authenticated path traversal flaw affecting Zohocorp ManageEngine M365 Manager Plus and M365 Security Plus versions prior to 4820 within their Exchange Online backup module. This security weakness stems from insufficient input validation and improper access controls that allow authenticated users to manipulate file paths and navigate beyond the intended directory structures. The flaw exists in the backup module's handling of user-supplied parameters during file operations, creating an opportunity for malicious actors with valid credentials to access unauthorized system resources.
From a technical perspective, this vulnerability manifests when the application fails to properly sanitize user inputs that are used to construct file paths or directory references within the Exchange Online backup functionality. The lack of proper validation mechanisms enables attackers to craft malicious requests containing directory traversal sequences such as ../ or ..\ that bypass normal access controls and permit arbitrary file system access. This type of vulnerability is classified under CWE-22 Path Traversal which represents one of the most prevalent and dangerous classes of vulnerabilities in web applications, particularly when combined with authentication requirements that lower the barrier to exploitation.
The operational impact of this authenticated path traversal vulnerability presents significant risks to organizations using affected ManageEngine versions. An attacker with legitimate user credentials could potentially access sensitive backup files, configuration data, or system logs that should remain restricted to authorized personnel only. This could lead to information disclosure, unauthorized data access, and potential escalation of privileges within the backup environment. The consequences extend beyond simple data exposure as attackers might gain access to backup archives containing credentials, system configurations, or other sensitive operational data that could be leveraged for further attacks against the broader network infrastructure.
The vulnerability aligns with several ATT&CK techniques including T1078 Valid Accounts for initial access and T1566 Phishing for credential acquisition if attackers exploit this flaw to escalate privileges or access additional accounts. Organizations utilizing these ManageEngine products face heightened risk of lateral movement within their environments once the path traversal has been successfully exploited, as backup systems often contain privileged information that can be used to compromise additional systems. The authenticated nature of this vulnerability means that attackers need to first obtain valid user credentials through phishing campaigns, credential stuffing attacks, or other social engineering techniques before they can exploit this specific weakness.
Mitigation strategies should focus on immediate remediation through patching affected ManageEngine versions to 4820 or later where the path traversal vulnerability has been addressed. Organizations must also implement network segmentation to limit access to backup systems and establish robust monitoring for unusual file access patterns that might indicate exploitation attempts. Additionally, regular security assessments of backup environments should be conducted to identify potential unauthorized access points, while privileged account management practices including multi-factor authentication and least privilege principles should be enforced to minimize the impact of credential compromise. The implementation of web application firewalls and input validation controls can provide additional layers of protection against similar vulnerabilities in other components of the system.