CVE-2026-53948

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.

CVSS v3.1 Score

5.4

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0013

Probability of exploitation

0.03%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-434 Unrestricted Upload

References

Other References

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

Frequently Asked Questions

What is CVE-2026-53948? +

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. It has a CVSS v3.1 base score of 5.4 (MEDIUM).

How severe is CVE-2026-53948? +

CVE-2026-53948 has a CVSS v3.1 score of 5.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0013, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-53948? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-3219

pip handles concatenated tar and ZIP files as ZIP files regardless of filename or whether a file is both a …

CVE-2024-43662

The <redacted>.exe or <redacted>.exe CGI binary can be used to upload arbitrary files to /tmp/upload/ or /tmp/ respectively as any …

CVE-2026-41517

Emlog is an open source website building system. Prior to version 2.6.11, insecure plugin upload functionality allows attackers to upload …

CVE-2026-5482

Responsive FileManager's allows an unauthenticated attacker to upload files of any type and extension without restriction using dialog.php endpoint, leading …

CVE-2026-34027

The Wertheim SafeController Software, AssemblyVersion 6.15.8328.28014, contains insufficient server-side file type validation in the /safe/contract/uploadcustomdocuments endpoint. The application validates uploaded …

CVE-2019-25714

Seeyon OA A8 contains an unauthenticated arbitrary file write vulnerability in the /seeyon/htmlofficeservlet endpoint that allows remote attackers to write …