CVE-2022-31546 in glance
Summary
by MITRE • 07/11/2022
The nlpweb/glance repository through 2014-06-27 on GitHub allows absolute path traversal because the Flask send_file function is used unsafely.
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Analysis
by VulDB Data Team • 07/21/2022
The vulnerability identified as CVE-2022-31546 resides within the nlpweb/glance repository, a project that appears to be a web application framework or tool for natural language processing tasks. This particular flaw manifests in the repository's handling of file operations, specifically through the improper use of the Flask send_file function. The issue is particularly concerning as it affects versions up to and including the 2014-06-27 release, indicating a long-standing vulnerability that was never properly addressed. The repository's web application architecture likely serves static files or user-generated content through Flask's built-in file serving capabilities, creating an attack surface where malicious actors can exploit improper input validation.
The technical root cause of this vulnerability stems from the unsafe implementation of Flask's send_file function, which is designed to securely serve files from the server to clients. When this function is invoked without proper parameter validation or sanitization, it becomes susceptible to path traversal attacks. The flaw allows attackers to manipulate file paths through user input, potentially enabling them to access files outside of the intended directory structure. This occurs because the application fails to properly validate or sanitize the file path parameters before passing them to send_file, which then processes these paths directly without adequate security checks.
The operational impact of this vulnerability is significant as it creates a direct pathway for unauthorized file access within the application's file system. An attacker could potentially traverse the file system to access sensitive configuration files, source code, database files, or other restricted resources that should not be publicly accessible. This type of vulnerability falls under the CWE-22 category of Path Traversal, which is classified as a critical security weakness that allows attackers to access files and directories that they should not be permitted to access. The implications extend beyond simple data theft, as this vulnerability could potentially lead to complete system compromise if sensitive files containing credentials, encryption keys, or application logic are accessed.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing for Information) as attackers could use this weakness to discover and extract sensitive information from the target system. The attack vector is particularly dangerous in web applications where the send_file function is commonly used to serve user-uploaded content or static assets. The vulnerability represents a classic example of insufficient input validation where user-controllable parameters are passed directly to file system functions without proper sanitization, making it an attractive target for exploitation.
The recommended mitigations for this vulnerability involve implementing proper input validation and sanitization of all file path parameters before they are passed to Flask's send_file function. Developers should employ absolute path resolution techniques that ensure file access remains within designated directories and implement proper access controls to prevent traversal beyond intended boundaries. Additionally, the application should validate file paths against a whitelist of allowed directories or use secure file handling libraries that properly sanitize user inputs. Organizations should also consider implementing proper logging and monitoring of file access patterns to detect potential exploitation attempts. The fix requires updating the repository code to properly validate and sanitize file paths, ensuring that the Flask send_file function receives only validated, safe inputs that cannot be manipulated to traverse the file system.