{"id":"GHSA-944x-pm95-3jpr","summary":"Ghost: File Upload Content-Type Spoofing","details":"### Impact\n\nInsufficient 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.\n\n### Vulnerable versions\n\nThis vulnerability is present in Ghost from v6.19.4 up to v6.21.0.\n\n### Patches\n\nv6.21.1 contains a fix for this issue.\n\n### How to update\n\nFor 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). \n\nIf your Ghost is a Ghost-CLI install see our documentation on [updating it to the latest version here](https://docs.ghost.org/update). \n\n### For more information\n\nIf you have any questions or comments about this advisory, email us at [security@ghost.org](mailto:security@ghost.org).","aliases":["BIT-ghost-2026-53948","CVE-2026-53948"],"modified":"2026-08-04T21:15:19.787379123Z","published":"2026-08-04T21:05:39Z","database_specific":{"github_reviewed_at":"2026-08-04T21:05:39Z","nvd_published_at":"2026-06-24T19:17:12Z","cwe_ids":["CWE-434"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/TryGhost/Ghost/security/advisories/GHSA-944x-pm95-3jpr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53948"},{"type":"WEB","url":"https://github.com/TryGhost/Ghost/pull/26751"},{"type":"WEB","url":"https://github.com/TryGhost/Ghost/commit/d659e752d6636144d75b9aa94062cdbc88a16b21"},{"type":"PACKAGE","url":"https://github.com/TryGhost/Ghost"},{"type":"WEB","url":"https://github.com/TryGhost/Ghost/releases/tag/v6.21.1"}],"affected":[{"package":{"name":"ghost","ecosystem":"npm","purl":"pkg:npm/ghost"},"ranges":[{"type":"SEMVER","events":[{"introduced":"6.19.4"},{"fixed":"6.21.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-944x-pm95-3jpr/GHSA-944x-pm95-3jpr.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"}]}