---
id: CVE-2026-53948
aliases:
  - GHSA-944x-pm95-3jpr
title: 'Ghost: File Upload Content-Type Spoofing'
summary: 'Ghost: File Upload Content-Type Spoofing'
severity: medium
cvss: 5.4
cwe:
  - CWE-434
vendor: ghost
product: ghost
ecosystem: npm
affected:
  - 'ghost >= 6.19.4, < 6.21.1'
patched:
  - ghost 6.21.1
published: '2026-08-04'
updated: '2026-08-04'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-944x-pm95-3jpr'
references:
  - url: 'https://github.com/TryGhost/Ghost/security/advisories/GHSA-944x-pm95-3jpr'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53948'
  - url: 'https://github.com/TryGhost/Ghost/pull/26751'
  - url: >-
      https://github.com/TryGhost/Ghost/commit/d659e752d6636144d75b9aa94062cdbc88a16b21
  - url: 'https://github.com/TryGhost/Ghost/releases/tag/v6.21.1'
  - url: 'https://github.com/advisories/GHSA-944x-pm95-3jpr'
tags:
  - ghsa
  - npm
epss: 0.00226
epssPercentile: 0.11886
ingestedAt: '2026-08-04T21:42:19.518Z'
---

## Overview

### Impact

Insufficient validation of the client-supplied `Content-Type` on Ghost's Admin API file upload endpoint allowed uploaded files to be served from the site with an attacker-chosen content type on S3/GCS storage backends. On installations that serve uploaded files from the same origin as the site, this could have been used to facilitate stored cross-site scripting against site visitors or staff.

### Vulnerable versions

This vulnerability is present in Ghost from v6.19.4 up to v6.21.0.

### Patches

v6.21.1 contains a fix for this issue.

### How to update

For self-hosters using Docker, find [Docker's official Ghost image here](https://hub.docker.com/_/ghost). Updating a Docker-based Ghost instance [is documented here](https://docs.ghost.org/install/docker#updating-ghost). 

If your Ghost is a Ghost-CLI install see our documentation on [updating it to the latest version here](https://docs.ghost.org/update). 

### For more information

If you have any questions or comments about this advisory, email us at [security@ghost.org](mailto:security@ghost.org).

## Affected packages

- `ghost >= 6.19.4, < 6.21.1`

## Remediation

Upgrade to a patched release:

- `ghost 6.21.1`