CVEs / CVE-2026-30821
CVE-2026-30821: FlowiseAI Flowise vulnerability
- critical 9.8 CVSS 3.1 (NVD)
- EPSS 16.7% chance of exploitation in the next 30 days, higher than 97% of CVEs (2 Nov 2026)
- Last changed at its sources
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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.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| FlowiseAI Flowise | < 3.0.13 | — |
| Product | Affected | Fixed in |
|---|---|---|
| flowise (npm) | before 3.0.13 | 3.0.13 |
Package versions from GHSA-j8g8-j7fc-43v6.
Exploitation
Not in the CISA Known Exploited Vulnerabilities catalog as of 30 Oct 2026.
Severity
| CVSS 3.1 | 9.8 criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HScored by NVD |
|---|---|
| Weakness | CWE-434 |
References
- CVE-2026-30821 on NVD
- CVE-2026-30821 on OSV
- https://github.com/FlowiseAI/Flowise/releases/tag/flowise%403.0.13 Product, Release Notes
- https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-j8g8-j7fc-43v6 Exploit, Vendor Advisory
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.