CVE-2025-48953: Umbraco.Cms Umbraco Vulnerable To By-Pass Of Vulnerability

MODERATE
Advisory Identifier: GHSA-fr6r-p8hv-x3c4
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CVSS 5.5
CWE-434
Published
Advisory Summary

CVE-2025-48953 is a MODERATE (CVSS 5.5) umbraco vulnerable to by-pass of vulnerability (CWE-434: Unrestricted Upload of File with Dangerous Type) affecting Umbraco.Cms libraries in the NuGet ecosystem. The issue involves umbraco vulnerable to by-pass of configured allowed extensions for file uploads. Remediation is available by upgrading affected packages to version 15.4.2.

CVE-2025-48953 at a Glance

CVE Identifier CVE-2025-48953
GHSA Identifier GHSA-fr6r-p8hv-x3c4
Severity MODERATE
CVSS v3.1 Base Score 5.5
CWE Classification CWE-434: Unrestricted Upload of File with Dangerous Type
Affected Product Umbraco.Cms
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 5.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:L).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2025-48953

To remediate this vulnerability, upgrade all affected Umbraco.Cms dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Umbraco.Cms fixed: 15.4.2 
Upgrade Umbraco.Cms to 15.4.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for Umbraco.Cms

How to Check if You Are Affected

To determine whether your application is affected by CVE-2025-48953, inspect your project dependencies for Umbraco.Cms:

inspect dependencies for Umbraco.Cms

Analyze the terminal output to locate any version of Umbraco.Cms in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 15.4.2), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-434: Unrestricted Upload of File with Dangerous Type, where the product allows the upload or transfer of dangerous file types that are automatically processed within its environment. In Umbraco.Cms, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Via a manipulated API request it's possible to upload a file that doesn't adhere with the configured allowable file extensions. ### Patches Patched in 15.4.2 and 16.0.0. ### Workarounds None available.

CVE-2025-48953 Affected Umbraco.Cms Versions

1 component(s)
Fixed Versions:
15.4.2
Product / Package Ecosystem Affected Versions Fixed Version
Umbraco.Cms
nuget/Umbraco.Cms
NuGet
≥ 14.0.0
< 15.4.2
15.4.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-fr6r-p8hv-x3c4
NVD — CVE-2025-48953 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-48953
Security Fix Commit FIX COMMIT
https://github.com/umbraco/Umbraco-CMS/commit/d920e93d1ee29dc3301697e444f53e8cd5db3cf9
Umbraco.Cms Source Repository REPOSITORY
https://github.com/umbraco/Umbraco-CMS

Frequently Asked Questions

What is CVE-2025-48953?
CVE-2025-48953 is a security vulnerability in Umbraco.Cms involving Umbraco Vulnerable to By-Pass of Configured Allowed Extensions for File Uploads under CWE-434: Unrestricted Upload of File with Dangerous Type.
Which Umbraco.Cms versions are affected?
Affected versions include releases prior to 15.4.2 across affected packages: Umbraco.Cms.
What version fixes CVE-2025-48953?
Upgrading to 15.4.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Umbraco.Cms affected?
Yes, Umbraco.Cms is affected in releases prior to 15.4.2. Upgrade your dependency to 15.4.2 or later.
What is the CVSS score of CVE-2025-48953?
CVE-2025-48953 has a CVSS v3.1 base score of 5.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:L.
What CWE is associated with CVE-2025-48953?
CVE-2025-48953 is classified under CWE-434: Unrestricted Upload of File with Dangerous Type (The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.).
How can I check NuGet dependencies for CVE-2025-48953?
Run the dependency tree command: 'inspect dependencies for Umbraco.Cms'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fr6r-p8hv-x3c4",
  "modified" : "2025-06-04T23:50:55Z",
  "published" : "2025-06-04T23:50:55Z",
  "aliases" : [ "CVE-2025-48953" ],
  "summary" : "Umbraco Vulnerable to By-Pass of Configured Allowed Extensions for File Uploads",
  "details" : "### Impact\nVia a manipulated API request it's possible to upload a file that doesn't adhere with the configured allowable file extensions.\n\n### Patches\nPatched in 15.4.2 and 16.0.0.\n\n### Workarounds\nNone available.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Umbraco.Cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "14.0.0"
      }, {
        "fixed" : "15.4.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 15.4.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-fr6r-p8hv-x3c4"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-48953"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/umbraco/Umbraco-CMS/commit/d920e93d1ee29dc3301697e444f53e8cd5db3cf9"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/umbraco/Umbraco-CMS"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-434" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-06-04T23:50:55Z",
    "nvd_published_at" : "2025-06-03T19:15:39Z"
  }
}