CVE-2026-116578 Tornado: Open redirect in RedirectHandler via protocol-relative URLs
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-116578?
CVE-2026-116578 is a low-severity vulnerability in tornadoweb tornado, published on 26 Oct 2026.
Official description
Tornado is a Python web framework and asynchronous networking library. Prior to 6.6, tornado.web.RedirectHandler URL templates can place regex-capture substitutions where crafted request paths change the redirect scheme or network location. Affected placements include substitutions at the start of a path, directly after a fixed host, or at the beginning of the template, including protocol-relative, absolute, backslash, encoded, host-extension, and user-info variants interpreted by browsers as attacker-controlled destinations. Static templates and substitutions after a fixed host followed by a slash are not affected. An attacker can use the resulting open redirect on the application's domain for phishing. This issue is fixed in version 6.6.
Weakness: CWE-601
Which versions are affected by CVE-2026-116578?
2 open source packages ship an affected version, including tornado.
| Package | Affected | Fixed in |
|---|---|---|
tornado PyPI | All versions | 6.6 |
tornado PyPI | All versions | 6.6 |
How do I fix CVE-2026-116578?
Upgrade tornado to 6.6 or later.
Is CVE-2026-116578 being exploited?
There is no known exploitation of CVE-2026-116578 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-116578, ECHO-b1d7-e956-461d, GHSA-pw9p-v7r6-gx4p, MINI-jqj6-pmxg-jwwj, UBUNTU-CVE-2026-116578.