{"id":"CVE-2026-31958","aliases":["GHSA-qjxf-f2mg-c6mc","PYSEC-2026-140"],"url":"https://o3.security/vulnerability/CVE-2026-31958","summary":"Tornado has a DoS due to too many multipart parts","details":"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.","published":"2026-03-11T19:27:23.380Z","modified":"2026-08-12T03:51:19.357901463Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"tornado","fixedVersion":"6.5.5"}],"fix":null,"references":[{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2026/04/msg00000.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31958.json"},{"type":"ADVISORY","url":"https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31958"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:19.357901463Z"}}