Fix path traversal vulnerability in actions.py using secure_filename#7
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Sanitize user-supplied filename to prevent path traversal attacks in the `/message` endpoint.
## Changes
- Added import for `werkzeug.utils.secure_filename`
- Applied `secure_filename()` to sanitize `filename_param` before constructing the file path
- Replaced string concatenation with `Path` operator for cleaner path construction
## Why
The `filename_param` parameter was taken directly from user input without validation. An attacker could supply a malicious filename like `../../etc/passwd` to write files outside the intended `data/{user_id}/` directory. Using `secure_filename()` strips path separators and other dangerous characters, ensuring the file is always written within the intended directory.
## Semgrep Finding Details
The application builds a file path from potentially untrusted data, which can lead to a path traversal vulnerability. An attacker can manipulate the path which the application uses to access files. If the application does not validate user input and sanitize file paths, sensitive files such as configuration or user data can be accessed, potentially creating or overwriting files. In Flask apps, consider using the Werkzeug util `werkzeug.utils.secure_filename()` to sanitize paths and filenames.
@267212124 requested Semgrep Assistant generate this pull request to fix [a finding](https://semgrep.dev/orgs/studentsca023_personal_org/findings/722169011) from the detection rule [python.flask.file.tainted-path-traversal-stdlib-flask.tainted-path-traversal-stdlib-flask](https://semgrep.dev/r/python.flask.file.tainted-path-traversal-stdlib-flask.tainted-path-traversal-stdlib-flask).
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Sanitize user-supplied filename to prevent path traversal attacks in the
/messageendpoint.Changes
werkzeug.utils.secure_filenamesecure_filename()to sanitizefilename_parambefore constructing the file pathPathoperator for cleaner path constructionWhy
The
filename_paramparameter was taken directly from user input without validation. An attacker could supply a malicious filename like../../etc/passwdto write files outside the intendeddata/{user_id}/directory. Usingsecure_filename()strips path separators and other dangerous characters, ensuring the file is always written within the intended directory.Semgrep Finding Details
The application builds a file path from potentially untrusted data, which can lead to a path traversal vulnerability. An attacker can manipulate the path which the application uses to access files. If the application does not validate user input and sanitize file paths, sensitive files such as configuration or user data can be accessed, potentially creating or overwriting files. In Flask apps, consider using the Werkzeug util
werkzeug.utils.secure_filename()to sanitize paths and filenames.@267212124 requested Semgrep Assistant generate this pull request to fix a finding from the detection rule python.flask.file.tainted-path-traversal-stdlib-flask.tainted-path-traversal-stdlib-flask.