TryGhost up to 6.21.0 API File Upload Endpoint unrestricted upload

Summaryinfo

A vulnerability marked as critical has been reported in TryGhost Ghost up to 6.21.0. Affected by this issue is some unknown functionality of the component API File Upload Endpoint. The manipulation leads to unrestricted upload. This vulnerability is uniquely identified as CVE-2026-53948. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in TryGhost Ghost up to 6.21.0. It has been rated as critical. This issue affects an unknown code of the component API File Upload Endpoint. The manipulation with an unknown input leads to a unrestricted upload vulnerability. Using CWE to declare the problem leads to CWE-434. The product allows the attacker to upload or transfer files of dangerous types that can be automatically processed within the product's environment. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-53948 since 06/11/2026. The exploitation is known to be easy. The attack may be initiated remotely. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1608.002 for this issue.

Upgrading to version 6.21.1 eliminates this vulnerability.

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Productinfo

Vendor

• TryGhost

Name

• Ghost

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16
• 6.17
• 6.18
• 6.19
• 6.20
• 6.21.0

Website

• Product: https://github.com/TryGhost/Ghost/

CPE 2.3info

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CPE 2.2info

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