{"id":"CVE-2026-53948","sourceIdentifier":"security-advisories@github.com","published":"2026-06-24T19:17:12.460","lastModified":"2026-06-25T16:07:28.730","vulnStatus":"Deferred","cveTags":[],"descriptions":[{"lang":"en","value":"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."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"TryGhost","product":"Ghost","versions":[{"version":">= 6.19.4, < 6.21.1","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","baseScore":5.4,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"REQUIRED","scope":"CHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"NONE"},"exploitabilityScore":2.3,"impactScore":2.7}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-06-25T13:17:17.045202Z","id":"CVE-2026-53948","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Secondary","description":[{"lang":"en","value":"CWE-434"}]}],"references":[{"url":"https://github.com/TryGhost/Ghost/security/advisories/GHSA-944x-pm95-3jpr","source":"security-advisories@github.com"}]}