Ghost: Stored XSS via Embed Card Previews

### Impact Embed cards in the Ghost editor could be used to bypass the fix for GHSA-8vhf-xxpj-4qrg. Any staff user, including Contributors, could store scripts in post content that ran when another staff user opened the post in the editor, possibly resulting in compromise of that user's admin session. Self-hosted sites should leave the new `security.embedPreviewUrl` config option at its default. ### Vulnerable versions This vulnerability is present in Ghost from v6.34.0 up to v6.65.0. ### Patches v6.67.0 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). ### References Ghost thanks [DONG2209 (Dong Nguyen)](https://github.com/DONG2209) and Pedro Pinho for disclosing this vulnerability responsibly. ### For more information If you have any questions or comments about this advisory, email us at [security@ghost.org](mailto:security@ghost.org). Source Code Location: https://github.com/TryGhost/Ghost Affected Packages: - npm:ghost, affected >= 6.34.0, < 6.67.0, patched in 6.67.0 CWEs: - CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') - CWE-653: Improper Isolation or Compartmentalization CVSS: - Primary: score 7.3, CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - CVSS_V3: score 7.3, CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N References: - https://github.com/TryGhost/Ghost/security/advisories/GHSA-69qc-f5m6-889c - https://github.com/penpot/penpot/security/advisories/GHSA-qvq5-c536-pmx8 - https://nvd.nist.gov/vuln/detail/CVE-2026-105643 - https://github.com/advisories/GHSA-69qc-f5m6-889c