CWE-25 (路径遍历：’/../filedir’) — Vulnerability Class 11

CWE-25 represents a critical input validation weakness where applications fail to properly sanitize external inputs before constructing file paths. Attackers typically exploit this vulnerability by injecting directory traversal sequences, such as “../”, into user-supplied parameters. These sequences allow the application to resolve paths outside the intended restricted directory, enabling unauthorized access to sensitive system files, configuration data, or other restricted resources. To mitigate this risk, developers must implement robust input validation strategies, strictly filtering or rejecting any path traversal characters before processing. Additionally, using canonicalization techniques to normalize paths and verifying that the resolved location remains within the designated secure boundary are essential defensive measures. Employing allow-lists for permitted file extensions and utilizing secure API functions that abstract direct file system access further reduces the attack surface, ensuring that user input cannot manipulate the underlying file structure.