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.
Metrics
Affected Vendors & Products
References
History
Mon, 09 Mar 2026 21:15:00 +0000
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ssvc
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Mon, 09 Mar 2026 10:15:00 +0000
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Flowiseai
Flowiseai flowise |
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| Vendors & Products |
Flowiseai
Flowiseai flowise |
Sat, 07 Mar 2026 05:15:00 +0000
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| 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. | |
| Title | Flowise: Arbitrary File Upload via MIME Spoofing | |
| Weaknesses | CWE-434 | |
| References |
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| Metrics |
cvssV4_0
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Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-03-07T05:07:50.067Z
Updated: 2026-03-09T20:44:24.875Z
Reserved: 2026-03-05T21:06:44.605Z
Link: CVE-2026-30821
Updated: 2026-03-09T20:35:42.568Z
Status : Awaiting Analysis
Published: 2026-03-07T05:16:26.907
Modified: 2026-03-09T13:35:34.633
Link: CVE-2026-30821
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