CVE intelligence

CVE-2026-126347

Vulnerability intelligence

Published Nov 12, 2026Sources checked Nov 13, 2026

3.1LOWCVSS out of 10

What this means

Review the available evidence

CVE-2026-126347 and is rated Low severity with a CVSS score of 3.1. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Nov 13, 2026

Release Notes

CISA KEVNot listedBased on the latest collected catalog

EPSSUnavailableNo current score collected

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-126347?

Tornado is a Python web framework and asynchronous networking library. In versions through 6.6.0, applications using tornado.web.RedirectHandler with URL templates that allow attacker-controlled substitutions to influence the destination can be vulnerable to an open redirect using three or more leading slashes.

Differences between Python’s URL parsing and browser URL interpretation allow a crafted destination to redirect a user to an attacker-controlled host. The remediation for CVE-2026-116578 in version 6.6.0 did not fully address this case.

This issue is fixed in version 6.6.1.

Source: NVD