CVE-2026-49853

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

HIGH
7.7
CVSS Score
Published: July 14, 2026 at 08:41 PM UTC
Updated: October 24, 2026 at 09:10 PM UTC
1 product affected across 1 vendorTornado

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Severity
HIGH7.7
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 6.5.6
Affected range stops below 6.5.6, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.7HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-200

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