CVE-2026-82397
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an unauthenticated request body containing millions of separator-delimited fields can synchronously stall the single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which defaults to 104857600 bytes. This issue is fixed in version 6.5.8.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| tornadoweb | tornado | < 6.5.8 | affected |
Weaknesses
- CWE-400: CWE-400: Uncontrolled Resource Consumption
- CWE-1284: CWE-1284: Improper Validation of Specified Quantity in Input
References
- https://github.com/tornadoweb/tornado/security/advisories/GHSA-mpf4-983q-p7j4
- https://github.com/tornadoweb/tornado/pull/3704
- https://github.com/tornadoweb/tornado/commit/8d6363ed7b69d5f0da806efe34d256627a2191de
- https://github.com/tornadoweb/tornado/releases/tag/v6.5.8
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