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How CVE-2026-70593 Works
Ghost is a Node.js-based open-source content management system. The vulnerability exists in how the platform handles custom theme uploads. From version 0.10.0 through 6.54.0, the theme upload functionality fails to properly sanitize user-supplied input when generating file paths for theme storage.
Specifically, the flaw resides in the `LocalStorageBase` component and the theme storage name handling routines. When a staff user uploads a custom theme, the system processes the theme name without adequate validation of special characters or directory traversal sequences such as `../` or ./. This allows an attacker to craft a theme zip file with a name containing path traversal payloads. During extraction, the application writes files to a location derived from the manipulated theme name, effectively escaping the intended `uploads` directory.
Because the vulnerability is triggered during the theme upload process, it requires the attacker to have staff-level privileges. Once authenticated, the attacker can upload a malicious theme that, when processed, writes arbitrary files anywhere on the server’s file system that the Ghost process has write access to. This could be used to overwrite critical configuration files, inject malicious code into existing templates, or place backdoors for persistent access.
The vulnerability is classified under CWE-22 (Path Traversal) and has been assigned a CVSS v3.1 score of 6.6, indicating a moderate severity. The attack vector is network-based, requires high complexity, and demands high privileges, but the scope is changed and the impact on integrity is high while availability is low. The fix in version 6.54.1 introduces proper input validation and path sanitization routines that block directory traversal sequences during theme uploads. Users are strongly advised to upgrade immediately or, if that is not possible, to restrict or disable the ability for staff users to upload custom themes until the patch is applied.
DailyCVE Form:
Platform: Ghost CMS
Version: v0.10.0–v6.54.0
Vulnerability: Path Traversal
Severity: Medium (CVSS 6.6)
date: 2026-08-04
Prediction: 2026-08-05
What Undercode Say: Analytics
Check Ghost version
ghost --version
List all staff users (potential attackers)
ghost user list --role staff
Monitor theme upload attempts in logs
grep -i "theme upload" /var/log/ghost/ghost.log
Search for suspicious files outside uploads directory
find / -type f -newer /path/to/ghost/uploads -exec ls -la {} \; 2>/dev/null | grep -v "uploads"
Audit for unexpected .hbs or .js files in core directories
find /path/to/ghost/current -type f ( -name ".hbs" -o -name ".js" ) -mtime -30 -ls
Exploit:
Craft a malicious theme zip with path traversal in the name mkdir malicious_theme echo " <h1>Hacked</h1> " > malicious_theme/index.hbs zip -r ../malicious_theme.zip malicious_theme/ Rename the zip to include traversal payload mv malicious_theme.zip "../../../config/../../malicious_theme.zip" Upload via Ghost Admin interface (requires staff credentials) curl -X POST https://target-ghost.com/ghost/api/admin/themes/upload/ \ -H "Authorization: Bearer <STAFF_TOKEN>" \ -F "file=@../../../config/../../malicious_theme.zip" Alternatively, use the Ghost Admin UI to upload the renamed zip The payload will write files to /path/to/ghost/config/ or similar
Protection:
- Upgrade to Ghost v6.54.1 or later immediately.
- If upgrade is not possible, restrict staff theme upload permissions via role settings.
- Implement Web Application Firewall (WAF) rules to block path traversal patterns (
../,./) in upload filenames. - Regularly audit the `uploads` directory and system logs for unexpected files or write attempts.
- Apply principle of least privilege: limit staff accounts to only necessary personnel.
Impact:
Successful exploitation allows an authenticated staff user to write arbitrary files anywhere on the server’s filesystem. This can lead to:
– Overwriting critical Ghost configuration files (e.g., config.production.json), altering application behavior.
– Injecting malicious code into theme templates or core JavaScript files, enabling persistent backdoors or defacement.
– Escalating privileges by modifying system files or creating new administrative users.
– Compromising the integrity and availability of the entire CMS instance, potentially affecting other services on the same host.
The vulnerability is particularly dangerous because it leverages legitimate staff credentials, making it harder to detect through traditional perimeter defenses.
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Sources:
Reported By: github.com
Extra Source Hub:
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