{"cve":{"cve_id":"CVE-2026-53537","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.00176,"epss_percentile":0.07179,"epss_as_of":"2026-06-23","description":"Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, parse_options_header parsed Content-Disposition (and Content-Type) headers with email.message.Message, which transparently applies RFC 2231/5987 decoding. The extended parameter syntax (filename*=charset'lang'value, name*=..., and the filename*0/filename*1 continuation form) is decoded and surfaced under the bare filename/name key, and overrides the plain parameter when both are present. RFC 7578 §4.2 explicitly forbids the filename* form in multipart/form-data. Components that follow RFC 7578, or that do not implement RFC 2231/5987 decoding for multipart/form-data (WAFs, proxies, gateways), may interpret such a header differently. An attacker can exploit that difference to smuggle a different field name or filename past an upstream inspector to the backend. This vulnerability is fixed in 0.0.30.","published_at":"2026-06-22T16:57:21.496000Z","last_modified_at":null,"cvss_v3_score":3.7,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","cvss_v3_severity":"LOW","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-20","CWE-436"],"nvd_references":["https://github.com/Kludex/python-multipart/security/advisories/GHSA-vffw-93wf-4j4q"],"vuln_status":null,"trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:39.878444Z","updated_at":"2026-06-28T23:30:52.348775Z"},"effective_severity":"LOW","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"H","value_label":"High"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"U","value_label":"Unchanged"},{"metric":"C","name":"Confidentiality","value":"N","value_label":"None"},{"metric":"I","name":"Integrity","value":"L","value_label":"Low"},{"metric":"A","name":"Availability","value":"N","value_label":"None"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"kludex","vendor_name":"Kludex","product_slug":"python-multipart","product_name":"python-multipart","version_start":"< 0.0.30","version_start_inclusive":true,"version_end":"< 0.0.30","version_end_inclusive":true,"cpe23_uri":"cve5:kludex:python-multipart:< 0.0.30:< 0.0.30"}],"exploit_refs":[],"news":[],"references":[{"url":"https://github.com/Kludex/python-multipart/security/advisories/GHSA-vffw-93wf-4j4q","source_type":"VENDOR_ADVISORY","tags":["advisory"]}],"timeline":[{"type":"published","at":"2026-06-22T16:57:21.496000Z","label":"CVE published","source":null},{"type":"cvss_changed","at":"2026-06-28T17:55:28.590503Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:55:28.590503Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:55:28.590503Z","label":"CVSS score revised","source":"cvelistv5"}]}