CVE-2025-66625
- CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
- Published: 2025-12-09T20:15:55.320
Umbraco is an ASP.NET CMS. Due to unsafe handling and deletion of temporary files in versions 10.0.0 through 13.12.0, during the dictionary upload process an attacker with access to the backoffice can trigger predictable requests to temporary file paths. The application’s error responses (HTTP 500 when a file exists, 404 when it does not) allow the attacker to enumerate the existence of arbitrary files on the server’s filesystem. This vulnerability does not allow reading or writing file contents. In certain configurations, incomplete clean-up of temporary upload files may additionally expose the NTLM hash of the Windows account running the Umbraco application. This issue is fixed in version 13.12.1.
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How to fix CVE-2025-66625
Description: Umbraco is an ASP.NET CMS. Due to unsafe handling and deletion of temporary files in versions 10.0.0 through 13.12.0, during the dictionary upload process an attacker with access to the backoffice can trigger predictable requests to temporary file paths. The application’s error responses (HTTP 500 when a file exists, 404 when it does not) allow […]
Affected Versions:
❌ Vulnerable: 10.0.0 - 13.12.0
✅ Safe: ≥ 13.12.1
Exploit Difficulty: MEDIUM
⏱️ Time to exploit: 1-4 hours
🛠️ Required skills: Intermediate security knowledge
💰 Public exploits: May be available
How to Fix:
- Check if you're running the affected product
- Verify version (vulnerable: 10.0.0 - 13.12.0)
- Update to ≥ 13.12.1 or later
- If patching is not immediately possible: restrict network exposure, apply least-privilege access
- Test the fix in a staging environment first
- Review logs for signs of exploitation
- Monitor for IOCs (Indicators of Compromise)
- Enable automatic security updates
- Set up vulnerability monitoring
- Review and harden security configurations
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