PYSEC-2026-140

vendorUSosv
view advisory published 2026-03-11Licence: CC-BY-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.

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describes (1)

Related CVEs.

IDseverity exploitable
CVE-2026-31958UShigh7.5—
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 ma…
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