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Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')


Severity High
Score 7.5/10


The package aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. When using aiohttp as a web server and configuring static routes, it is necessary to specify the root path for static files. Additionally, the option 'follow_symlinks' can be used to determine whether to follow symbolic links outside the static root directory. When 'follow_symlinks' is set to True, there is no validation to check if reading a file is within the root directory. This can lead to Directory Traversal vulnerabilities, resulting in unauthorized access to arbitrary files on the system, even when symlinks are not present. Disabling "follow_symlinks" and using a reverse proxy are encouraged mitigation. This vulnerability affects aiohttp package versions 1.1.0 through 3.9.1, 4.0.0a0 and 4.0.0a1.

  • LOW
  • NONE
  • NONE
  • NONE
  • HIGH
  • NONE

CWE-22 - Path Traversal

Path traversal (or directory traversal), is a vulnerability that allows malicious users to traverse the server's root directory, gaining access to arbitrary files and folders such as application code & data, back-end credentials, and sensitive operating system files. In the worst-case scenario, an attacker could potentially execute arbitrary files on the server, resulting in a denial of service attack. Such an exploit may severely impact the integrity, confidentiality, and availability of an application.

Advisory Timeline

  • Published