CVE-2026-53537

{"id": "CVE-2026-53537", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-53537", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-06-23T16:03:15.384645Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 3.7, "attackVector": "NETWORK", "baseSeverity": "LOW", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 1.4, "exploitabilityScore": 2.2}, {"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 1.4, "exploitabilityScore": 3.9}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "Kludex", "product": "python-multipart", "versions": [{"status": "affected", "version": "< 0.0.30"}]}]}], "published": "2026-06-22T18:16:44.077", "references": [{"url": "https://github.com/Kludex/python-multipart/security/advisories/GHSA-vffw-93wf-4j4q", "tags": ["Vendor Advisory"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-20"}, {"lang": "en", "value": "CWE-436"}]}], "descriptions": [{"lang": "en", "value": "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 \u00a74.2 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."}, {"lang": "es", "value": "Python-Multipart es un analizador multipart de streaming para Python. Antes de la versi\u00f3n 0.0.30, parse_options_header analizaba los encabezados Content-Disposition (y Content-Type) con email.message.Message, que aplica de forma transparente la decodificaci\u00f3n RFC 2231/5987. La sintaxis de par\u00e1metro extendida (filename=charset\u2019lang\u2019value, name=..., y la forma de continuaci\u00f3n filename0/filename1) se decodifica y se expone bajo la clave filename/name simple, y anula el par\u00e1metro simple cuando ambos est\u00e1n presentes. RFC 7578 \u00a74.2 proh\u00edbe expl\u00edcitamente la forma filename en multipart/form-data. Los componentes que siguen RFC 7578, o que no implementan la decodificaci\u00f3n RFC 2231/5987 para multipart/form-data (WAFs, proxies, gateways), pueden interpretar dicho encabezado de manera diferente. Un atacante puede explotar esa diferencia para introducir un nombre de campo o nombre de archivo diferente m\u00e1s all\u00e1 de un inspector ascendente hacia el backend. Esta vulnerabilidad est\u00e1 corregida en la versi\u00f3n 0.0.30."}], "lastModified": "2026-10-25T23:10:00.167", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:fastapiexpert:python-multipart:*:*:*:*:*:python:*:*", "vulnerable": true, "matchCriteriaId": "381A8F1D-278D-409F-974A-898BE65DB20C", "versionEndExcluding": "0.0.30"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}