medium

CVE-2026-53948

npm · ghost

Summary

Ghost: File Upload Content-Type Spoofing

Severity
medium
CVSS
5.4
EPSS
0.2% (p13)
CWE
CWE-434
Also known as
GHSA-944x-pm95-3jpr
Published
2026-08-04
Updated
2026-08-04

Advisory details

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.

References

Related advisories

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.