Tornado before 6.5.9 StaticFileHandler Path Traversal via Symlink

Advisories

Tornado before 6.5.9 StaticFileHandler Path Traversal via Symlink

severity: high
date: 10/1/2026
Affecting: tornado >= 0, < 6.5.9
CVE: CVE-2026-103263
CWE: CWE-59 Improper Link Resolution Before File Access ('Link Following')
CVSS: 8.2
CVSS V4 Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
References: GitHub Security Advisory (GHSA-c2m8-h5v5-343r)
https://github.com/tornadoweb/tornado/commit/437ab5f76565403b3403438d2e555d11f8128d32
Credit: Yasha-ops, iaohkut-from-NightWolf-Team
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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