High severity · published Jul 14, 2026
CVE-2026-49853
Tornado: Authorization header forwarded across cross-origin redirects in SimpleAsyncHTTPClient
7.7
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 39% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
TO
tornado · tornadoweb
< 6.5.6 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-49853
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-49853
github.com
https://github.com/tornadoweb/tornado/commit/aba2569f7ed7a6bdbef816658fb6b7182531b751
github.com
https://github.com/tornadoweb/tornado/pull/3626
github.com
https://github.com/tornadoweb/tornado/releases/tag/v6.5.6
github.com
https://github.com/tornadoweb/tornado/security/advisories/GHSA-3x9g-8vmp-wqvf
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