Listen to this Post
How CVE-2026-70595 Works
This vulnerability is a Server-Side Request Forgery (SSRF) flaw present in Ghost CMS from version 6.26.0 up to, but not including, 6.54.1. The core of the issue lies in a validation bypass within the handling of outbound HTTP requests, specifically those triggered by features such as Webmentions.
Under normal operation, Ghost’s Webmention functionality allows the server to make HTTP requests to external URLs to verify and process incoming mentions. However, due to insufficient validation of user-supplied input, an unauthenticated attacker can manipulate these requests. The vulnerability allows an attacker to coerce the Ghost server into making HTTP requests to hosts on its own internal network. This is achieved by bypassing the private-IP check that is designed to prevent such internal calls.
By crafting a malicious request to the Webmention endpoint, an attacker can effectively use the Ghost server as a proxy to scan internal IP addresses and ports. The attack is limited in scope, as it only allows for outbound HTTP requests without returning any response data to the attacker. This means that while the attacker can determine if a host or service is reachable, they cannot directly read the data returned from those internal services.
The vulnerability affects all self-hosted instances of Ghost running the vulnerable versions. The Ghost team has addressed this issue in version 6.54.1 by implementing a more robust validation mechanism for outbound requests. The fix, which can be seen in the associated commit, strengthens the input sanitization and URL validation to prevent this type of SSRF attack.
DailyCVE Form:
Platform: Ghost CMS
Version: 6.26.0-6.54.0
Vulnerability: Server-Side Request Forgery
Severity: Medium
Date: 2026-08-05
Prediction: 2026-08-06
What Undercode Say: Analytics
The following commands and code snippets are relevant for analyzing and understanding this vulnerability.
Checking Ghost Version:
To determine if your instance is vulnerable, you can check the version from the Ghost admin panel or via the command line.
Navigate to your Ghost installation directory cd /path/to/ghost Check the current version ghost version
Viewing the Fix Commit:
The patch for this vulnerability was introduced in commit a8bea3a. You can view the changes that fixed the SSRF issue.
Clone the Ghost repository (if you haven't already) git clone https://github.com/TryGhost/Ghost.git Navigate to the repository cd Ghost View the specific commit that contains the fix git show a8bea3a4ceec4c852b880f4885119453c3d8588e
This commit shows the implementation of DOMPurify sanitization and link protocol validation which closes the SSRF vector.
How Exploit: CVE-2026-70595
An unauthenticated attacker can exploit this vulnerability by sending a crafted HTTP request to the Webmention endpoint. The request would contain a URL that points to an internal IP address or hostname within the Ghost server’s network.
Example of a malicious request:
POST /webmentions/receive/ HTTP/1.1 Host: vulnerable-ghost-site.com Content-Type: application/x-www-form-urlencoded source=http://internal-host-ip:port/&target=http://vulnerable-ghost-site.com/post-url/
In this example, the `source` parameter is manipulated to point to an internal host. When the Ghost server processes this request, it attempts to fetch the URL, thereby probing the internal network.
Protection: From this CVE
The primary and most effective protection against CVE-2026-70595 is to upgrade Ghost to version 6.54.1 or later. This version contains the official patch that resolves the validation issue.
Upgrade Instructions:
For Docker-based installations: Pull the latest official Ghost Docker image and restart your container.
docker pull ghost:latest docker-compose down && docker-compose up -d
For Ghost-CLI installations: Run the following command in your Ghost installation directory.
ghost update
As a temporary mitigation, if an immediate upgrade is not possible, consider disabling features that trigger outbound fetches, such as Webmentions and oEmbed, to reduce the attack surface.
Impact: CVE-2026-70595
The impact of this vulnerability is a Server-Side Request Forgery (SSRF) attack. An unauthenticated attacker can abuse the Webmention functionality to make the Ghost server send HTTP requests to hosts on its internal network. While the attack does not expose response data, it allows an attacker to perform internal network scanning. This can be used to map internal infrastructure and identify live hosts and services, which could be a precursor to further, more damaging attacks. The vulnerability is rated as Medium severity.
🎯Let’s Practice Exploiting & Learn Patching For Free:
🎓 Live Courses & Certifications:
Join Undercode Academy for Verified Certifications
🚀 Request a Custom Project:
Secure, high-velocity infrastructure and disruptive technological engineering. Contact our engineering team for high-tier development and proprietary systems:
[email protected]
💎 Smart Architecture | 🛡️ Secure by Design | ⭐ Trusted by Thousands
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
