CVE-2026-49853: Tornadoweb Tornado

High severity, CVSS 7.7. EPSS: 0.5% chance of exploitation in the next 30 days.

Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, SimpleAsyncHTTPClient shallow-copied redirected requests and removed only the Host header, leaving Authorization, auth_username, auth_password, and auth_mode in place when a redirect changed scheme, host, or port. This issue is fixed in version 6.5.6.

Affected products

• Tornadoweb Tornado: before 6.5.6 (fixed in 6.5.6)

Published 2026-07-14. Last modified 2026-07-21.