CVE-2026-40321: DotNetNuke.Core Cross-Site Scripting Vulnerability

HIGH
Advisory Identifier: GHSA-ffq7-898w-9jc4
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CVSS 8.0
CWE-87
Published
Advisory Summary

CVE-2026-40321 is a HIGH (CVSS 8.0) cross-site scripting vulnerability (CWE-87: Improper Neutralization of Alternate XSS Syntax) affecting DotNetNuke.Core libraries in the NuGet ecosystem. The issue involves dotnetnuke.core has stored cross-site-scripting (xss) via svg upload. Remediation is available by upgrading affected packages to version 10.2.2.

CVE-2026-40321 at a Glance

CVE Identifier CVE-2026-40321
GHSA Identifier GHSA-ffq7-898w-9jc4
Severity HIGH
CVSS v3.1 Base Score 8.0
CWE Classification CWE-87: Improper Neutralization of Alternate XSS Syntax
Affected Product DotNetNuke.Core
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 8.0

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:H/I:H/A:H).

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 High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-40321

To remediate this vulnerability, upgrade all affected DotNetNuke.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.

DotNetNuke.Core fixed: 10.2.2 
Upgrade DotNetNuke.Core to 10.2.2
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 DotNetNuke.Core

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-40321, inspect your project dependencies for DotNetNuke.Core:

inspect dependencies for DotNetNuke.Core

Analyze the terminal output to locate any version of DotNetNuke.Core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 10.2.2), 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-87: Improper Neutralization of Alternate XSS Syntax, where the product does not neutralize or incorrectly neutralizes user-controlled input for alternate script syntax. In DotNetNuke.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

DNN (formerly DotNetNuke) is an open-source web content management platform (CMS) in the Microsoft ecosystem. Prior to version 10.2.2, a user could upload a specially crafted SVG file that could include scripts that can target both authenticated and unauthenticated DNN users. The impact is increased if the scripts are run by a power user. Version 10.2.2 patches the issue.

CVE-2026-40321 Affected DotNetNuke.Core Versions

1 component(s)
Fixed Versions:
10.2.2
Product / Package Ecosystem Affected Versions Fixed Version
DotNetNuke.Core
nuget/DotNetNuke.Core
NuGet
< 10.2.2
10.2.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/dnnsoftware/Dnn.Platform/security/advisories/GHSA-ffq7-898w-9jc4
NVD — CVE-2026-40321 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-40321
DotNetNuke.Core Source Repository REPOSITORY
https://github.com/dnnsoftware/Dnn.Platform
DotNetNuke.Core Release RELEASE
https://github.com/dnnsoftware/Dnn.Platform/releases/tag/v10.2.2

Frequently Asked Questions

What is CVE-2026-40321?
CVE-2026-40321 is a security vulnerability in DotNetNuke.Core involving DotNetNuke.Core has stored cross-site-scripting (XSS) via SVG upload under CWE-87: Improper Neutralization of Alternate XSS Syntax.
Which DotNetNuke.Core versions are affected?
Affected versions include releases prior to 10.2.2 across affected packages: DotNetNuke.Core.
What version fixes CVE-2026-40321?
Upgrading to 10.2.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is DotNetNuke.Core affected?
Yes, DotNetNuke.Core is affected in releases prior to 10.2.2. Upgrade your dependency to 10.2.2 or later.
What is the CVSS score of CVE-2026-40321?
CVE-2026-40321 has a CVSS v3.1 base score of 8.0 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H.
What CWE is associated with CVE-2026-40321?
CVE-2026-40321 is classified under CWE-87: Improper Neutralization of Alternate XSS Syntax (The product does not neutralize or incorrectly neutralizes user-controlled input for alternate script syntax.).
How can I check NuGet dependencies for CVE-2026-40321?
Run the dependency tree command: 'inspect dependencies for DotNetNuke.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-ffq7-898w-9jc4",
  "modified" : "2026-04-24T20:50:37Z",
  "published" : "2026-04-10T20:42:48Z",
  "aliases" : [ "CVE-2026-40321" ],
  "summary" : "DotNetNuke.Core has stored cross-site-scripting (XSS) via SVG upload",
  "details" : "DNN (formerly DotNetNuke) is an open-source web content management platform (CMS) in the Microsoft ecosystem. Prior to version 10.2.2, a user could upload a specially crafted SVG file that could include scripts that can target both authenticated and unauthenticated DNN users. The impact is increased if the scripts are run by a power user. Version 10.2.2 patches the issue.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "DotNetNuke.Core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "10.2.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/dnnsoftware/Dnn.Platform/security/advisories/GHSA-ffq7-898w-9jc4"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-40321"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/dnnsoftware/Dnn.Platform"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/dnnsoftware/Dnn.Platform/releases/tag/v10.2.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-87" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-10T20:42:48Z",
    "nvd_published_at" : "2026-04-17T22:16:32Z"
  }
}