CVE-2026-115927

Tornado is a Python web framework and asynchronous networking library. Prior to 6.6.0, Tornado decodes HTTP/1.1 chunked transfer encoding by processing body data that has already arrived without yielding to the event loop. A remote unauthenticated peer can send millions of one-byte chunks to monopolize the process event loop and stall every other connection served by that process, while lowering max_body_size only limits the duration of each request. For handlers that do not use @stream_request_body, retaining each chunk as a separate object can consume roughly twenty times the received body size, and SimpleAsyncHTTPClient has the same event-loop behavior when reading a response from a malicious server. This issue is fixed in version 6.6.0.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
https://github.com/tornadoweb/tornado/commit/ceab33581489751a66fba8566ad6d5960d4b01c8
https://github.com/tornadoweb/tornado/pull/3773
https://github.com/tornadoweb/tornado/releases/tag/v6.6.0
https://github.com/tornadoweb/tornado/security/advisories/GHSA-r4j5-9xpp-3985

Configurations

No configuration.

History

26 Oct 2026, 20:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-26 20:17

Updated : 2026-10-27 15:16

NVD link : CVE-2026-115927

Mitre link : CVE-2026-115927

CVE.ORG link : CVE-2026-115927

JSON object : View

Products Affected

No product.

CWE

CWE-400

Uncontrolled Resource Consumption

CWE-770

Allocation of Resources Without Limits or Throttling

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