Nhost Storage Affected by MIME Type Spoofing via Trusted Client Content-Type Header in Storage Upload

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.1 · CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-33221: 0.18% estimated exploitation activity in the next 30 days; percentile 7.59 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The storage service's file upload handler trusts the client-provided Content-Type header without performing server-side MIME type detection. This allows an attacker to upload files with an arbitrary MIME type, bypassing any MIME-type-based restrictions configured on storage buckets. Affected Component - Service: services/storage - File: services/storage/controller/uploadfiles.go - Function: getMultipartFile (lines 48-70) Root Cause In getMultipartFile, if the client provides a non-empty Content-Type header that isn't application/octet-stream, the function returns it as-is without performing content-based detection: Impact Incorrect MIME type in file metadata. The MIME type stored in file metadata reflects what the client claims rather than what the file actually contains. Any system consuming this metadata (browsers, CDNs, applications) may handle the file incorrectly based on the spoofed type. Suggested Fix Always detect MIME type from file content using…

Published by the source

18 Mar 2026, 20:21 UTC

Last modified by the source

9 Jun 2026, 11:52 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-g9f6-9775-hffm

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# Patch Next advisory brief: CVE-2026-33221

Advisory: Nhost Storage Affected by MIME Type Spoofing via Trusted Client Content-Type Header in Storage Upload
IDs: CVE-2026-33221, GHSA-g9f6-9775-hffm
Record: https://patchnext.com/advisories/cve-2026-33221 (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/nhost/nhost 0.0.0-20260318074820-c4bd53f042d7. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/nhost/nhost: affected < 0.0.0-20260318074820-c4bd53f042d7; fixed in 0.0.0-20260318074820-c4bd53f042d7

## Suggested inspection (read-only)
- Go github.com/nhost/nhost: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/nhost/nhost.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-g9f6-9775-hffm (GitHub-reviewed advisory GHSA-g9f6-9775-hffm lists affected ranges: Go github.com/nhost/nhost >=0 <0.0.0-20260318074820-c4bd53f042d7)

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