CVE-2026-127203
AppFlowy Cloud 0.9.64 Stored XSS via Blob Upload Content-Type
AppFlowy Cloud through 0.9.64 contains a stored cross-site scripting vulnerability that allows authenticated workspace members to upload blobs with unvalidated Content-Type values that are later served inline without a Content-Disposition header or authentication on the retrieval route. Attackers can upload a text/html or image/svg+xml blob via put_blob_handler, which is then rendered as an active same-origin document through the unauthenticated get_blob_handler endpoint and cached immutably for one year, enabling persistent script execution against any visitor who accesses the URL.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| AppFlowy-Cloud AppFlowy-IO AppFlowy-IO/AppFlowy-Cloud
github |
≥ 0; ≤ 0.9.64 (affected, semver)
Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 5.1 medium |
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N | CNA: VulnCheck |
| 3.1 / 5.4 medium |
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N | CNA: VulnCheck |
| 4.0 / 5.1 medium |
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD: [email protected] |
| 3.1 / 5.4 medium |
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N | NVD: [email protected] |
Exploit evidence
- https://gist.github.com/mtholmquist/9b9683104fc3b5d78a488c06a6674e5c
exploit · CNA: VulnCheck
References
- https://gist.github.com/mtholmquist/9b9683104fc3b5d78a488c06a6674e5cCNA: VulnCheck · technical-description, exploit
- https://www.vulncheck.com/advisories/appflowy-cloud-stored-xss-via-blob-upload-content-typeCNA: VulnCheck · third-party-advisory
- https://gist.github.com/mtholmquist/9b9683104fc3b5d78a488c06a6674e5c[email protected]
- https://www.vulncheck.com/advisories/appflowy-cloud-stored-xss-via-blob-upload-content-type[email protected]
For agents and automation
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