Ghost: File Upload Content-Type Spoofing
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. Updating a Docker-based Ghost instance is documented here.
If your Ghost is a Ghost-CLI install see our documentation on updating it to the latest version here.
For more information
If you have any questions or comments about this advisory, email us at security@ghost.org.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | ghost | >= 6.19.4, < 6.21.1 | 6.21.1 |
References
- https://github.com/TryGhost/Ghost/security/advisories/GHSA-944x-pm95-3jpr
- https://nvd.nist.gov/vuln/detail/CVE-2026-53948
- https://github.com/TryGhost/Ghost/pull/26751
- https://github.com/TryGhost/Ghost/commit/d659e752d6636144d75b9aa94062cdbc88a16b21
- https://github.com/TryGhost/Ghost
- https://github.com/TryGhost/Ghost/releases/tag/v6.21.1
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-434- Platform
- npm
- Package
ghost- Disclosed
- 04.08.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-944x-pm95-3jpr - CC BY 4.0
Vulnerability history: ghost
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 61
- First → latest
- 04.2021 10.2026
- Without a fix
- 3
- Exploited in attacks
- 0
Severity breakdown
- Critical 4
- High 16
- Medium 38
- Low 3
Disclosures per year
- 2021: 5
- 2022: 4
- 2023: 3
- 2024: 3
- 2025: 1
- 2026: 45
-
Ghost: File Upload Content-Type Spoofing this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.