EUVD-2026-53388
GHSA-x5mm-wm4g-j5xv
Severity by source
AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N
Network-accessible unauthenticated feature; S:C for internal network boundary crossing; C:L for blind probe-only SSRF; no integrity or availability impact; AC:H consistent with vendor-assigned vector and blind exploitation constraint.
Primary rating from Vendor (https://github.com/TryGhost/Ghost).
CVSS VectorVendor: https://github.com/TryGhost/Ghost
Lifecycle Timeline
3DescriptionCVE.org
Impact
A validation issue allowed some functionality, such as Webmentions, to be abused by an unauthenticated user to make limited HTTP requests to hosts in the Ghost server's internal network. A successful attack would not result in any response data being returned.
Vulnerable versions
This vulnerability is present in Ghost from v6.26.0 up to v6.54.0.
Patches
v6.54.1 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 Hwang Seyeon for disclosing this vulnerability responsibly.
For more information
If you have any questions or comments about this advisory, email Ghost at [security@ghost.org](mailto:security@ghost.org).
AnalysisAI
Server-Side Request Forgery in Ghost CMS v6.26.0-v6.54.0 allows unauthenticated remote attackers to abuse features such as Webmentions to issue blind HTTP requests from the Ghost server into its internal network, bypassing perimeter controls without returning response content to the attacker. The flaw stems from insufficient URL validation in outbound HTTP request handling, enabling internal host probing across a changed security scope (CVSS S:C). No active exploitation (CISA KEV) or public POC has been identified at time of analysis; the vendor has released a fix in v6.54.1.
Technical ContextAI
Ghost is a Node.js open-source CMS distributed as the npm package pkg:npm/ghost. The Webmentions protocol (W3C standard) requires Ghost to make outbound HTTP requests to URLs sourced from user-submitted content - a classic SSRF-enabling pattern. CWE-918 (Server-Side Request Forgery) identifies the root cause: user-controlled URLs are not sufficiently validated before the server's HTTP client executes them, allowing private or non-routable addresses (RFC 1918 ranges, link-local metadata endpoints such as 169.254.169.254, or loopback) to be targeted. The CVSS S:C (Scope Changed) metric confirms that exploitation crosses a security boundary: the vulnerable component is Ghost, but the exploited resource is the internal network infrastructure beyond it. The pkg:npm/ghost CPE covers both Docker-based and Ghost-CLI self-hosted deployments.
RemediationAI
Upgrade Ghost to v6.54.1 or later, which contains the vendor-confirmed validation fix for this issue. For Docker-based deployments, pull the updated official image from hub.docker.com/_/ghost following the upgrade guide at https://docs.ghost.org/install/docker#updating-ghost. For Ghost-CLI installations, follow the standard upgrade procedure at https://docs.ghost.org/update. If immediate patching is not feasible, implement egress firewall rules on the Ghost host to block outbound HTTP/HTTPS requests to RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), loopback (127.0.0.0/8), and link-local ranges (169.254.0.0/16) - note this may partially disrupt legitimate internal integrations. If the Webmentions feature is not used, disabling it removes one confirmed attack vector, though the advisory notes other features may share the same validation gap. Contact Ghost security at security@ghost.org for questions per the advisory.
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External POC / Exploit Code
Leaving vuln.today