CVE-2026-116577

Tornado is a Python web framework and asynchronous networking library. Prior to 6.6, Tornado's HTTP header parser accepts obsolete line folding and repeatedly concatenates short continuation lines, causing quadratic CPU consumption on the IOLoop thread. An unauthenticated client can submit a header block containing many obsolete line-folding continuations before application code runs, blocking other connections served by the process. The cost grows with max_header_size, and only availability is affected. This issue is fixed in version 6.6.

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/1b7a1dc9f340f52de929852e8125aa12f25297c9
https://github.com/tornadoweb/tornado/pull/3765
https://github.com/tornadoweb/tornado/releases/tag/v6.6.0
https://github.com/tornadoweb/tornado/security/advisories/GHSA-pcg2-g6cj-q92c

Configurations

No configuration.

History

26 Oct 2026, 21:18

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-26 21:18

Updated : 2026-10-31 02:17

NVD link : CVE-2026-116577

Mitre link : CVE-2026-116577

CVE.ORG link : CVE-2026-116577

JSON object : View

Products Affected

No product.

CWE

CWE-407

Inefficient Algorithmic Complexity

CWE-770

Allocation of Resources Without Limits or Throttling

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