High

aiohttp is vulnerable to directory traversal

  • Disclosed: 29.01.2024
  • Updated: 11.10.2026 15:17

Summary

Improperly configuring static resource resolution in aiohttp when used as a web server can result in the unauthorized reading of arbitrary files on the system.

Details

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 a given file path 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.

i.e. An application is only vulnerable with setup code like:

app.router.add_routes([
    web.static("/static", "static/", follow_symlinks=True),  # Remove follow_symlinks to avoid the vulnerability
])

Impact

This is a directory traversal vulnerability with CWE ID 22. When using aiohttp as a web server and enabling static resource resolution with follow_symlinks set to True, it can lead to this vulnerability. This vulnerability has been present since the introduction of the follow_symlinks parameter.

Workaround

Even if upgrading to a patched version of aiohttp, we recommend following these steps regardless.

If using follow_symlinks=True outside of a restricted local development environment, disable the option immediately. This option is NOT needed to follow symlinks which point to a location within the static root directory, it is only intended to allow a symlink to break out of the static directory. Even with this CVE fixed, there is still a substantial risk of misconfiguration when using this option on a server that accepts requests from remote users.

Additionally, aiohttp has always recommended using a reverse proxy server (such as nginx) to handle static resources and not to use these static resources in aiohttp for production environments. Doing so also protects against this vulnerability, and is why we expect the number of affected users to be very low.


Patch: https://github.com/aio-libs/aiohttp/pull/8079/files

Affected software

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PlatformPackageVulnerable versionsFixed in
Python (PyPI) aiohttp >= 1.0.5, < 3.9.2 3.9.2

References

CVSS score 5.9/10
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE)
CWE-22
Platform
Python (PyPI)
Package
aiohttp
Disclosed
29.01.2024
Updated
11.10.2026 15:17

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2024-24 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-5h86-8mv2-jq9f - CC BY 4.0

Vulnerability history: aiohttp

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (55) in the archive
Total entries
55
First → latest
02.2021 10.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 7
  • Medium 29
  • Low 19

Disclosures per year

  1. 2021: 1
  2. 2022: 0
  3. 2023: 6
  4. 2024: 7
  5. 2025: 1
  6. 2026: 40
Severity:
  1. High CVE-2026-111066 >= 2.0.0, < 3.14.4 3.14.4
  2. High CVE-2026-111064 < 3.14.4 3.14.4
  3. aiohttp is vulnerable to directory traversal this entry
    High · 5.9 CVE-2024-23334 >= 1.0.5, < 3.9.2 3.9.2

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