{"cve":"CVE-2026-30821","nvd":{"published":"2026-03-07T05:16:26.907","modified":"2026-06-17T10:32:58.443","status":"Analyzed","description":"Flowise is a drag & drop user interface to build a customized large language model flow. Prior to version 3.0.13, the /api/v1/attachments/:chatflowId/:chatId endpoint is listed in WHITELIST_URLS, allowing unauthenticated access to the file upload API. While the server validates uploads based on the MIME types defined in chatbotConfig.fullFileUpload.allowedUploadFileTypes, it implicitly trusts the client-provided Content-Type header (file.mimetype) without verifying the file's actual content (magic bytes) or extension (file.originalname). Consequently, an attacker can bypass this restriction by spoofing the Content-Type as a permitted type (e.g., application/pdf) while uploading malicious scripts or arbitrary files. Once uploaded via addArrayFilesToStorage, these files persist in backend storage (S3, GCS, or local disk). This vulnerability serves as a critical entry point that, when chained with other features like static hosting or file retrieval, can lead to Stored XSS, malicious file hosting, or Remote Code Execution (RCE). This issue has been patched in version 3.0.13.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","score":8.2},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-434"],"references":["https://github.com/FlowiseAI/Flowise/releases/tag/flowise%403.0.13","https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-j8g8-j7fc-43v6"],"products":["flowiseai:flowise"],"source":"nvd","synced_at":"2026-10-19T22:25:53.701907451+00:00"},"epss":{"cve":"CVE-2026-30821","score":0.15236,"percentile":0.96762,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-j8g8-j7fc-43v6","url":"https://osv.dev/vulnerability/GHSA-j8g8-j7fc-43v6","summary":"Flowise has Arbitrary File Upload via MIME Spoofing","modified":"2026-03-09T13:31:23.339258Z","packages":[{"ecosystem":"npm","name":"flowise","purl":"pkg:npm/flowise","ranges":["<3.0.13"],"fixed":["3.0.13"]}]}],"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."]}