Is CVE-2026-53948 in the CISA KEV catalog?

No. CVE-2026-53948 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-53948?

CVE-2026-53948 has a CVSS v3 base score of 5.4 (MEDIUM).

What is the EPSS score for CVE-2026-53948?

CVE-2026-53948 has an EPSS score of 0.13% (3th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2026-53948?

No published fix for CVE-2026-53948 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-53948

MEDIUM

5.4

CVSS v3

NVD

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.

CWE-434Unrestricted File Upload

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.13%probability of exploitation in 30 days

3rdpercentile

Low risk: more likely to be exploited than 3% of all known CVEs.

References

Other references1

github.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-25.