GHSA-g9f6-9775-hffm
MEDIUMNhost Storage Affected by MIME Type Spoofing via Trusted Client Content-Type Header in Storage Upload
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
github.com/nhost/nhostReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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/upload_files.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:
contentType := file.header.Header.Get("Content-Type")
if contentType != "" && contentType != "application/octet-stream" {
return fileContent, contentType, nil // skip detection entirely
}
// mimetype.DetectReader only reached if client sends no Content-Type
// or sends application/octet-stream
mt, err := mimetype.DetectReader(fileContent)
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 mimetype.DetectReader, ignoring the client-provided Content-Type header entirely.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/nhost/nhost | all versions | 0.0.0-20260318074820-c4bd53f042d7 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/nhost/nhost. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/nhost/nhost to 0.0.0-20260318074820-c4bd53f042d7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g9f6-9775-hffm is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-g9f6-9775-hffm is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-g9f6-9775-hffm. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-g9f6-9775-hffm in your dependencies?
O3 detects GHSA-g9f6-9775-hffm across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.