CVE-2026-103263
Deferred Deferred - Pending Action

Path Traversal in Tornado Web Framework

Publication date: 2026-10-01

Last updated on: 2026-10-01

Assigner: VulnCheck

Description
Tornado before 6.5.9 contains a path traversal vulnerability in StaticFileHandler that follows symbolic links inside the static root without confirming the resolved target stays within it. When a symlink pointing outside the static directory exists inside it, unauthenticated attackers can request it to read files such as configuration files, private keys, and application secrets accessible to the process user.

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Meta Information

Published
2026-10-01
Last Modified
2026-10-01
Generated
2026-10-01
AI Q&A
2026-10-01
EPSS Evaluated
N/A
NVD
CVE-2026-103263
EUVD
EUVD-2026-90657

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
tornadoweb tornado to 6.5.9 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-59 The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

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Executive Summary

This is a path traversal vulnerability in Tornado's StaticFileHandler before version 6.5.9. It allows unauthenticated attackers to read arbitrary files outside the intended static root directory by exploiting symbolic links. The handler follows symlinks without validating their targets, enabling access to sensitive files like configuration files or private keys.

Detection Guidance

To detect this vulnerability, check if your Tornado application uses StaticFileHandler with a static root directory that may contain symlinks. Inspect the Tornado version; if it is below 6.5.9, the system is vulnerable. Review logs for unusual file access patterns or requests to sensitive paths like /etc/passwd or configuration files.

  • Check Tornado version: pip show tornado or grep -r "tornado==" requirements.txt
  • Search for symlinks in static directories: find /path/to/static -type l
  • Monitor file access logs for requests outside the static root.
Impact Analysis

Attackers could access sensitive files such as configuration files, private keys, or application secrets if symlinks exist in the static directory. This could lead to data breaches, unauthorized access, or further exploitation of the system.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection principles or HIPAA's security requirements. Non-compliance may result in legal penalties, fines, or reputational damage.

Mitigation Strategies

Upgrade Tornado to version 6.5.9 or later immediately. If upgrading is not possible, disable StaticFileHandler or restrict access to the static directory. Ensure no symlinks exist in the static root that point outside the intended directory. Review and remove any user-uploaded symlinks.

  • Upgrade Tornado: pip install --upgrade tornado>=6.5.9
  • Disable StaticFileHandler if not required.
  • Audit static directories for malicious symlinks and remove them.

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