{"cve":"CVE-2026-40347","nvd":{"published":"2026-04-18T00:16:38.520","modified":"2026-10-26T21:10:00.170","status":"Analyzed","description":"Python-Multipart is a streaming multipart parser for Python. Versions prior to 0.0.26 have a denial of service vulnerability when parsing crafted `multipart/form-data` requests with large preamble or epilogue sections. Upgrade to version 0.0.26 or later, which skips ahead to the next boundary candidate when processing leading CR/LF data and immediately discards epilogue data after the closing boundary.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-400","CWE-834"],"references":["https://github.com/Kludex/python-multipart/releases/tag/0.0.26","https://github.com/Kludex/python-multipart/security/advisories/GHSA-mj87-hwqh-73pj"],"products":["fastapiexpert:python-multipart"],"source":"nvd","synced_at":"2026-10-26T21:38:48.864438205+00:00"},"epss":{"cve":"CVE-2026-40347","score":0.00351,"percentile":0.28483,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-mj87-hwqh-73pj","url":"https://osv.dev/vulnerability/GHSA-mj87-hwqh-73pj","summary":"python-multipart affected by Denial of Service via large multipart preamble or epilogue data","modified":"2026-09-10T03:51:02.322677211Z","packages":[{"ecosystem":"PyPI","name":"python-multipart","purl":"pkg:pypi/python-multipart","ranges":["<0.0.26"],"fixed":["0.0.26"]}]},{"id":"PYSEC-2026-3038","url":"https://osv.dev/vulnerability/PYSEC-2026-3038","summary":"python-multipart affected by Denial of Service via large multipart preamble or epilogue data","modified":"2026-07-13T16:33:29.086443165Z","packages":[{"ecosystem":"PyPI","name":"python-multipart","purl":"pkg:pypi/python-multipart","ranges":["<0.0.26"],"fixed":["0.0.26"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}