CVE-2022-22931 in James
Summary
by MITRE • 02/07/2022
Fix of CVE-2021-40525 do not prepend delimiters upon valid directory validations. Affected implementations include: - maildir mailbox store - Sieve file repository This enables a user to access other users data stores (limited to user names being prefixed by the value of the username being used).
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Analysis
by VulDB Data Team • 02/11/2022
The vulnerability identified as CVE-2022-22931 represents a critical authorization flaw in email server implementations that affects directory traversal and access control mechanisms. This issue specifically impacts maildir mailbox stores and Sieve file repositories, where the remediation for a previous vulnerability CVE-2021-40525 was insufficiently implemented. The flaw stems from the improper handling of directory validation processes, where the system fails to prepend necessary delimiters when validating directory paths, creating a pathway for unauthorized data access.
The technical implementation of this vulnerability occurs within the validation logic of directory access controls. When a user attempts to access mailbox data or Sieve repository files, the system performs directory validation checks to ensure proper access boundaries. However, due to the missing delimiter prepending mechanism, an authenticated user can manipulate directory paths to traverse into other users' data stores. This occurs because the validation process does not properly sanitize or normalize path components, allowing crafted directory references to bypass access controls.
The operational impact of this vulnerability is significant within multi-user email environments where data isolation is paramount. An attacker with valid user credentials can potentially access other users' mailbox contents or Sieve filter configurations, leading to information disclosure and potential data compromise. The scope of access is limited to user names that are prefixed by the current username being used, which means the vulnerability creates a horizontal privilege escalation scenario rather than a complete system compromise. This aligns with CWE-22 Directory Traversal and CWE-285 Improper Authorization patterns, where path traversal mechanisms fail to properly validate access boundaries.
The vulnerability demonstrates a classic security misconfiguration in access control implementation where the fix for one issue inadvertently created another. The remediation for CVE-2021-40525 was insufficiently comprehensive, leaving the underlying directory validation logic vulnerable to manipulation. This creates a persistent risk in email infrastructure where user isolation is compromised, potentially exposing sensitive communications and automated email processing rules. The flaw operates at the application level within the mail server software, making it particularly dangerous as it can be exploited without requiring elevated privileges beyond standard user access.
Mitigation strategies for CVE-2022-22931 should focus on implementing robust path validation and normalization mechanisms that ensure proper delimiter handling during directory access operations. Organizations should update their mail server implementations to properly prepend and validate path delimiters, ensuring that directory traversal attempts are properly bounded and authorized. The solution requires comprehensive testing of directory access controls and implementation of proper input sanitization to prevent path manipulation attacks. Security teams should also implement monitoring for unusual directory access patterns and conduct regular vulnerability assessments of email infrastructure components. This vulnerability highlights the importance of thorough regression testing when implementing security fixes and demonstrates the potential for seemingly minor implementation flaws to create significant access control bypass opportunities. The remediation process should follow ATT&CK technique T1078 Valid Accounts and T1566 Phishing to ensure that access controls are properly enforced and that unauthorized access attempts are detected and prevented.