What’s Vulnerable › Vulnerabilities

CVE-2026-49853: Tornado: Authorization header forwarded across cross-origin redirects in SimpleAsyncHTTPClient

• Severity: high (CVSS 7.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-14 · updated 2026-10-24
• Weakness: CWE-200

Description

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

• Pypi Tornado: before 6.5.6; 0.2, 1.0, 1.1, 1.1.1, 1.2, 1.2.1 (+75) — fixed in 6.5.6
• tornadoweb tornado: before 6.5.6

How to fix

Upgrade to a fixed version: Pypi Tornado 6.5.6. Check the vendor advisory for mitigations.

References

• https://github.com/tornadoweb/tornado/commit/aba2569f7ed7a6bdbef816658fb6b7182531b751
• https://github.com/tornadoweb/tornado/pull/3626
• https://github.com/tornadoweb/tornado/releases/tag/v6.5.6
• https://github.com/tornadoweb/tornado/security/advisories/GHSA-3x9g-8vmp-wqvf

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