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How the Mentioned CVE Works
The vulnerability exists in Ghost’s “External Media Inliner” feature. When a staff user with a valid Admin API token creates or edits content with an external image URL, the Ghost backend server attempts to fetch and inline that image. The vulnerable code does not properly validate or restrict the URL scheme or destination. An attacker can craft a request with a URL pointing to an internal, non-public service (e.g., http://169.254.169.254/ for cloud metadata, http://localhost:9200/ for Elasticsearch, or internal admin panels). The Ghost server, operating from within the trusted network, performs the HTTP request to the attacker-specified internal endpoint. This allows the attacker to exfiltrate sensitive data from these internal systems by having the server relay the response, effectively using the Ghost application as a proxy to bypass network security boundaries.
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Platform: Ghost CMS
Version: 5.38.0-5.130.5
Version: 6.0.0-6.10.3
Vulnerability: Server-Side Request Forgery
Severity: Moderate
date: 2026-01-08
Prediction: Patch available now
What Undercode Say
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curl -H "Authorization: Ghost <admin_token>" -X POST http://ghost.local/ghost/api/admin/posts/ -d '{"posts":[{"":"Test","html":"<img src=\"http://169.254.169.254/latest/meta-data/\">"}]}'
Monitor server outbound requests to internal IP ranges.
Check application logs for fetch events to localhost/private IPs.
How Exploit
1. Attacker obtains a compromised staff API key.
- Crafts a Ghost Admin API request to create a post containing an image tag pointing to an internal service URL.
- Submits the request. The Ghost server fetches the specified internal URL.
- Attractor extracts sensitive data from the server’s response, which may be embedded in the post, returned in an error, or observable through side-channels.
Protection from this CVE
1. Immediately upgrade to Ghost v5.130.6 or v6.11.0.
- Implement network segmentation to restrict backend servers from accessing sensitive internal services.
- Validate and sanitize all user-supplied URLs, rejecting those targeting localhost, private IPs, or internal domains.
- Use a dedicated allowlist of permissible external domains for media inlining if the feature is required.
Impact
1. Data exfiltration from internal networks.
2. Potential escalation to access cloud metadata credentials.
3. Bypass of firewall protections via server-side requests.
4. Compromise of other internal, non-public web services.
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Sources:
Reported By: github.com
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