{"id":"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.","aliases":["GHSA-qjxf-f2mg-c6mc"],"modified":"2026-04-03T07:59:16.212126762Z","published":"2026-03-11T19:27:23.380Z","related":["CGA-3jmv-9445-5g47","SUSE-SU-2026:1064-1","SUSE-SU-2026:1162-1","SUSE-SU-2026:1171-1","SUSE-SU-2026:20761-1","SUSE-SU-2026:20770-1","SUSE-SU-2026:20797-1","SUSE-SU-2026:20919-1","openSUSE-SU-2026:10374-1","openSUSE-SU-2026:10389-1","openSUSE-SU-2026:20406-1"],"database_specific":{"cwe_ids":["CWE-400"],"cna_assigner":"GitHub_M","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31958.json"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/tornadoweb/tornado","events":[{"introduced":"0"},{"fixed":"7d6465056ceb7a054b3f64cf1c18271753b10482"}]}],"versions":["v1.0.0","v1.0.1","v1.1.0","v1.1.1","v1.2.0","v1.2.1","v2.0.0","v2.1.0","v2.1.1","v2.2.0","v2.2.1","v2.3.0","v2.4.0","v2.4.1","v3.0.0","v3.0.1","v3.0.2","v3.1.0","v3.1.1","v3.2.0","v3.2.0b1","v3.2.0b2","v3.2.1","v3.2.2","v4.0.0","v4.0.0b1","v4.0.0b2","v4.0.0b3","v4.0.1","v4.0.2","v4.1.0","v4.1.0b1","v4.1.0b2","v4.2.0","v4.2.0b1","v4.2.1","v4.3.0","v4.3.0b1","v4.3.0b2","v4.4.0","v4.4.0b1","v4.4.1","v4.4.2","v4.4.3","v4.5.0","v4.5.1","v4.5.2","v4.5.3","v5.0.0","v5.0.1","v5.0.2","v5.1.0","v5.1.0b1","v5.1.1","v6.0.0","v6.0.0b1","v6.0.1","v6.0.2","v6.0.3","v6.0.4","v6.1.0","v6.1.0b1","v6.1.0b2","v6.2.0","v6.2.0b1","v6.2.0b2","v6.3.0","v6.3.0b1","v6.3.1","v6.3.2","v6.3.3","v6.4.0","v6.4.0b1","v6.4.1","v6.4.2","v6.5.0","v6.5.0b1","v6.5.1","v6.5.2","v6.5.3","v6.5.4"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31958.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}