CVE-2020-9471: UmbracoCMS.Core Umbraco CMS Authenticated File Upload Vulnerability

HIGH
Advisory Identifier: GHSA-h68c-4jh3-cp9j
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CVSS 8.8
CWE-434
Published
Advisory Summary

CVE-2020-9471 is a HIGH (CVSS 8.8) umbraco cms authenticated file upload vulnerability (CWE-434: Unrestricted Upload of File with Dangerous Type) affecting UmbracoCMS.Core libraries in the NuGet ecosystem. The issue involves umbraco cms authenticated file upload. Remediation is available in the latest vendor maintenance releases.

CVE-2020-9471 at a Glance

CVE Identifier CVE-2020-9471
GHSA Identifier GHSA-h68c-4jh3-cp9j
Severity HIGH
CVSS v3.1 Base Score 8.8
CWE Classification CWE-434: Unrestricted Upload of File with Dangerous Type
Affected Product UmbracoCMS.Core
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 8.8

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

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2020-9471

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

UmbracoCMS.Core fixed: Latest secure release 
Upgrade UmbracoCMS.Core to Latest secure release
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 UmbracoCMS.Core

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-9471, inspect your project dependencies for UmbracoCMS.Core:

inspect dependencies for UmbracoCMS.Core

Analyze the terminal output to locate any version of UmbracoCMS.Core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), 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 UmbracoCMS.Core, 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

Umbraco Cloud 8.5.3 allows an authenticated file upload (and consequently Remote Code Execution) via the Install Packages functionality.

CVE-2020-9471 Affected UmbracoCMS.Core Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
UmbracoCMS.Core
nuget/UmbracoCMS.Core
NuGet
≤ 8.5.3

References

NVD — CVE-2020-9471 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-9471
UmbracoCMS.Core Source Repository REPOSITORY
https://github.com/umbraco/Umbraco-CMS
gitlab.com/elen3re/cve-2020-94... WEB
https://gitlab.com/eLeN3Re/cve-2020-9471
gitlab.com/elen3re/cve-2020-94... WEB
https://gitlab.com/eLeN3Re/cve-2020-9472/-/blob/master/CVE-2020-9472.pdf

Frequently Asked Questions

What is CVE-2020-9471?
CVE-2020-9471 is a security vulnerability in UmbracoCMS.Core involving Umbraco CMS Authenticated File Upload under CWE-434: Unrestricted Upload of File with Dangerous Type.
Which UmbracoCMS.Core versions are affected?
Affected versions include releases prior to current release patches across affected packages: UmbracoCMS.Core.
What version fixes CVE-2020-9471?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is UmbracoCMS.Core affected?
Yes, UmbracoCMS.Core is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2020-9471?
CVE-2020-9471 has a CVSS v3.1 base score of 8.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2020-9471?
CVE-2020-9471 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-2020-9471?
Run the dependency tree command: 'inspect dependencies for UmbracoCMS.Core'. 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-h68c-4jh3-cp9j",
  "modified" : "2023-07-13T17:07:47Z",
  "published" : "2022-05-24T17:11:40Z",
  "aliases" : [ "CVE-2020-9471" ],
  "summary" : "Umbraco CMS Authenticated File Upload",
  "details" : "Umbraco Cloud 8.5.3 allows an authenticated file upload (and consequently Remote Code Execution) via the Install Packages functionality.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "UmbracoCMS.Core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "8.5.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-9471"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/umbraco/Umbraco-CMS"
  }, {
    "type" : "WEB",
    "url" : "https://gitlab.com/eLeN3Re/cve-2020-9471"
  }, {
    "type" : "WEB",
    "url" : "https://gitlab.com/eLeN3Re/cve-2020-9472/-/blob/master/CVE-2020-9472.pdf"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-434" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-07-13T17:07:47Z",
    "nvd_published_at" : "2020-03-16T20:15:00Z"
  }
}