CVE-2026-31958 — Tornado has a DoS due to too many multipart parts
Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the…
Published: 2026-03-11 · CVSS: 8.7 · CVSS 4.0
Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7