CVE-2026-33221Network attack vector

File-type restriction bypass via trusted Content-Type

Published Mar 20, 2026 · Updated Mar 20, 2026

MIME type spoofing in Nhost Storage before 0.12.0 allows remote attackers to bypass bucket file-type restrictions during uploads. The getMultipartFile function in services/storage/controller/upload_files.go returns a nonempty, non-octet-stream Content-Type header as the stored MIME type instead of detecting the file content. The bypass matters when a bucket enforces MIME-type restrictions or a downstream browser, CDN, or application trusts that metadata, limiting the direct result to false file metadata and policy evasion.

CVSS severity2.1
Low
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

MIME type spoofing in Nhost Storage before 0.12.0 allows remote attackers to bypass bucket file-type restrictions during uploads. The getMultipartFile function in services/storage/controller/upload_files.go returns a nonempty, non-octet-stream Content-Type header as the stored MIME type instead of detecting the file content. The bypass matters when a bucket enforces MIME-type restrictions or a downstream browser, CDN, or application trusts that metadata, limiting the direct result to false file metadata and policy evasion.

The record

CVE
CVE-2026-33221
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
Nhost
Product
Nhost
Classifications
CWE-434, CWE-345, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.12.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nhost · Nhostversion=< 0.12.0

Published CVSS scores

5.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
2.1GitHubCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
CWE-345Insufficient Verification of Data Authenticity
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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