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Fencer Vulns
medium 4.9

CVE-2025-66625 json

Umbraco Vulnerable to Improper File Access and Credential Exposure through Dictionary Import Functionality

published 2025-12-09 11 mo ago modified 2026-10-14 25 d ago also GHSA-hfv2-pf68-m33x , EUVD-2025-202178

cvss
4.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 29%
public exploits
0
none known

Summary

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.

Patch / fix

  • nuget Umbraco.Cms 13.12.1
  • umbraco umbraco_cms 13.12.1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
10 mo ago

Exploit prediction

0.36% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
GitHub 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
nuget Umbraco.Cms
>=10.0.0, <13.12.1
13.12.1

Affected products

  • umbraco Umbraco-CMS

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-377 DEPRECATED: Insecure Temporary File
  • CWE-552 Files or Directories Accessible to External Parties

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.