Allocation of Resources Without Limits or Throttling Affecting tornado package, versions [,6.5.8)
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- published2 Sept 2026
- disclosed1 Sept 2026
- creditafldl
Introduced: 1 Sep 2026
New CVE NOT AVAILABLE CWE-770 (opens in a new tab)How to fix?
Upgrade tornado to version 6.5.8 or higher.
Overview
tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed.
Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via parse_multipart_form_data in tornado/httputil.py, where the max_parts limit was enforced only after splitting the entire multipart body into parts. An attacker can send a multipart request with an excessive number of boundary-delimited parts, causing the str.split() call to allocate a large temporary list before the limit check is applied, resulting in CPU and memory amplification. The fix passes config.max_parts + 1 as the maxsplit argument so the split is bounded before the check.