CVE-2021-23428: ElFinder.NetCore Path Traversal Vulnerability

HIGH
Advisory Identifier: GHSA-9rjp-r58j-fxgq
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CVSS 8.6
CWE-20 CWE-22
Published
Advisory Summary

CVE-2021-23428 is a HIGH (CVSS 8.6) path traversal vulnerability (CWE-20: Improper Input Validation) affecting ElFinder.NetCore libraries in the NuGet ecosystem. The issue involves path traversal in elfinder.netcore. Remediation is available in the latest vendor maintenance releases.

CVE-2021-23428 at a Glance

CVE Identifier CVE-2021-23428
GHSA Identifier GHSA-9rjp-r58j-fxgq
Severity HIGH
CVSS v3.1 Base Score 8.6
CWE Classification CWE-20: Improper Input Validation
Affected Product ElFinder.NetCore
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 8.6

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

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

How to Fix CVE-2021-23428

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

elFinder.NetCore fixed: Latest secure release 
Upgrade elFinder.NetCore 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 elFinder.NetCore

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-23428, inspect your project dependencies for ElFinder.NetCore:

inspect dependencies for elFinder.NetCore

Analyze the terminal output to locate any version of ElFinder.NetCore 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-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In ElFinder.NetCore, 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

This affects all versions of package elFinder.NetCore. The Path.Combine(...) method is used to create an absolute file path. Due to missing sanitation of the user input and a missing check of the generated path its possible to escape the Files directory via path traversal

CVE-2021-23428 Affected ElFinder.NetCore Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
elFinder.NetCore
nuget/elFinder.NetCore
NuGet
≤ 1.3.5

References

NVD — CVE-2021-23428 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-23428
ElFinder.NetCore Source Repository REPOSITORY
https://github.com/gordon-matt/elFinder.NetCore
ElFinder.NetCore Source Repository REPOSITORY
https://github.com/gordon-matt/elFinder.NetCore/blob/633da9a4d7d5c9baefd1730ee51bf7af54889600/elFinder.NetCore/Drivers/FileSystem/FileSystemDriver.cs#L387
ElFinder.NetCore Source Repository REPOSITORY
https://github.com/gordon-matt/elFinder.NetCore/blob/633da9a4d7d5c9baefd1730ee51bf7af54889600/elFinder.NetCore/Drivers/FileSystem/FileSystemDriver.cs%23L387
snyk.io/vuln/snyk-dotnet-el... WEB
https://snyk.io/vuln/SNYK-DOTNET-ELFINDERNETCORE-1313838

Frequently Asked Questions

What is CVE-2021-23428?
CVE-2021-23428 is a security vulnerability in ElFinder.NetCore involving Path traversal in elFinder.NetCore under CWE-20: Improper Input Validation.
Which ElFinder.NetCore versions are affected?
Affected versions include releases prior to current release patches across affected packages: elFinder.NetCore.
What version fixes CVE-2021-23428?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is elFinder.NetCore affected?
Yes, elFinder.NetCore 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-2021-23428?
CVE-2021-23428 has a CVSS v3.1 base score of 8.6 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L.
What CWE is associated with CVE-2021-23428?
CVE-2021-23428 is classified under CWE-20: Improper Input Validation (The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.).
How can I check NuGet dependencies for CVE-2021-23428?
Run the dependency tree command: 'inspect dependencies for elFinder.NetCore'. 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-9rjp-r58j-fxgq",
  "modified" : "2021-09-02T18:03:47Z",
  "published" : "2021-09-02T22:05:26Z",
  "aliases" : [ "CVE-2021-23428" ],
  "summary" : "Path traversal in elFinder.NetCore",
  "details" : "This affects all versions of package elFinder.NetCore. The Path.Combine(...) method is used to create an absolute file path. Due to missing sanitation of the user input and a missing check of the generated path its possible to escape the Files directory via path traversal",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "elFinder.NetCore"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.3.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-23428"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/gordon-matt/elFinder.NetCore"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gordon-matt/elFinder.NetCore/blob/633da9a4d7d5c9baefd1730ee51bf7af54889600/elFinder.NetCore/Drivers/FileSystem/FileSystemDriver.cs#L387"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gordon-matt/elFinder.NetCore/blob/633da9a4d7d5c9baefd1730ee51bf7af54889600/elFinder.NetCore/Drivers/FileSystem/FileSystemDriver.cs%23L387"
  }, {
    "type" : "WEB",
    "url" : "https://snyk.io/vuln/SNYK-DOTNET-ELFINDERNETCORE-1313838"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20", "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-09-02T18:03:47Z",
    "nvd_published_at" : "2021-09-01T15:15:00Z"
  }
}