CVE-2026-53944: Ghost: Private IP filtering bypass to make server-side requests to internal services
Impact
When making an external request, it is possible to bypass the IP filter that ensures the request isn't going to an internal service using an IPv6 literal which maps to a private IPv4 address.
Vulnerable versions
This vulnerability is present in Ghost from v6.0.9 up to v6.21.0.
Patches
v6.21.1 contains a fix for this issue.
How to update
For self-hosters using Docker, find Docker's official Ghost image here. Updating a Docker-based Ghost instance is documented here.
If your Ghost is a Ghost-CLI install see our documentation on updating it to the latest version here.
References
Ghost thanks l3tchupkt for disclosing this vulnerability responsibly.
For more information
If you have any questions or comments about this advisory, email us at security@ghost.org.
Other sources
Ghost is a Node.js content management system. From 6.0.9 until 6.21.1, when making an external request, it is possible to bypass the IP filter that ensures the request isn't going to an internal service using an IPv6 literal which maps to a private IPv4 address. This vulnerability is fixed in 6.21.1.
— NVD
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/ghostto a version that resolves this vulnerability.Fixed in 6.21.1 - Upgrade
Upgrade
Ghostto a version that resolves this vulnerability.Fixed in 6.21.1
Event History
Frequently Asked Questions
What is the severity of CVE-2026-53944?
CVE-2026-53944 has a severity rating of medium, with a score of 5.8.
How do I fix CVE-2026-53944?
To fix CVE-2026-53944, update Ghost to version 6.21.1 or later.
What type of vulnerability is CVE-2026-53944?
CVE-2026-53944 is classified as a Server-Side Request Forgery (SSRF) vulnerability.
What impact does CVE-2026-53944 have on user privacy?
CVE-2026-53944 can lead to unauthorized access to internal services, potentially compromising user privacy.
Which versions of Ghost are affected by CVE-2026-53944?
CVE-2026-53944 affects Ghost versions from 6.0.9 until 6.21.1.