Open Redirect Affecting tornado package, versions [,6.6)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-TORNADO-21755373
- published27 Oct 2026
- disclosed26 Oct 2026
- creditLongwei Wang
Introduced: 26 Oct 2026
NewCVE-2026-116578 (opens in a new tab)How to fix?
Upgrade tornado to version 6.6 or higher.
Overview
tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed.
Affected versions of this package are vulnerable to Open Redirect via RedirectHandler in tornado/web.py when the redirect target URL is constructed from user-supplied input. If a user-controlled value appears at the start of the formatted URL, an attacker can supply a value beginning with a slash to produce a protocol-relative URL (e.g. //evil.example.com), causing the browser to follow a redirect to an arbitrary external host. The fix refuses to redirect to any URL starting with // unless the configured pattern itself starts with //.