CVE-2025-56236: FormCMS Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-4fxf-xgrm-8fcj
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CWE-434 CWE-79
Published
Advisory Summary

CVE-2025-56236 is a MODERATE cross-site scripting vulnerability (CWE-434: Unrestricted Upload of File with Dangerous Type) affecting FormCMS libraries in the NuGet ecosystem. The issue involves formcms avatar upload feature has a stored cross-site scripting (xss) vulnerability. Remediation is available by upgrading affected packages to version 0.5.7.

CVE-2025-56236 at a Glance

CVE Identifier CVE-2025-56236
GHSA Identifier GHSA-4fxf-xgrm-8fcj
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-434: Unrestricted Upload of File with Dangerous Type
Affected Product FormCMS
Package Ecosystem NuGet
Published Date
Last Updated

How to Fix CVE-2025-56236

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

FormCMS fixed: 0.5.7 
Upgrade FormCMS to 0.5.7
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 FormCMS

How to Check if You Are Affected

To determine whether your application is affected by CVE-2025-56236, inspect your project dependencies for FormCMS:

inspect dependencies for FormCMS

Analyze the terminal output to locate any version of FormCMS in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.5.7), 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 FormCMS, 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

FormCms v0.5.5 contains a stored cross-site scripting (XSS) vulnerability in the avatar upload feature. Authenticated users can upload .html files containing malicious JavaScript, which are accessible via a public URL. When a privileged user accesses the file, the script executes in their browser context.

CVE-2025-56236 Affected FormCMS Versions

1 component(s)
Fixed Versions:
0.5.7
Product / Package Ecosystem Affected Versions Fixed Version
FormCMS
nuget/FormCMS
NuGet
< 0.5.7
0.5.7

References

NVD — CVE-2025-56236 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-56236
FormCMS Source Repository REPOSITORY
https://github.com/FormCms/FormCms/issues/27
FormCMS Source Repository REPOSITORY
https://github.com/KKC73/me/blob/main/CVE-2025-56236/README.md
FormCMS Source Repository REPOSITORY
https://github.com/formcms/formcms

Frequently Asked Questions

What is CVE-2025-56236?
CVE-2025-56236 is a security vulnerability in FormCMS involving FormCms avatar upload feature has a stored cross-site scripting (XSS) vulnerability under CWE-434: Unrestricted Upload of File with Dangerous Type.
Which FormCMS versions are affected?
Affected versions include releases prior to 0.5.7 across affected packages: FormCMS.
What version fixes CVE-2025-56236?
Upgrading to 0.5.7 (or the latest patched release for your respective branch) resolves the vulnerability.
Is FormCMS affected?
Yes, FormCMS is affected in releases prior to 0.5.7. Upgrade your dependency to 0.5.7 or later.
What CWE is associated with CVE-2025-56236?
CVE-2025-56236 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-2025-56236?
Run the dependency tree command: 'inspect dependencies for FormCMS'. 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-4fxf-xgrm-8fcj",
  "modified" : "2025-08-28T16:47:04Z",
  "published" : "2025-08-28T15:30:42Z",
  "aliases" : [ "CVE-2025-56236" ],
  "summary" : "FormCms avatar upload feature has a stored cross-site scripting (XSS) vulnerability",
  "details" : "FormCms v0.5.5 contains a stored cross-site scripting (XSS) vulnerability in the avatar upload feature. Authenticated users can upload .html files containing malicious JavaScript, which are accessible via a public URL. When a privileged user accesses the file, the script executes in their browser context.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "FormCMS"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.5.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-56236"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FormCms/FormCms/issues/27"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/KKC73/me/blob/main/CVE-2025-56236/README.md"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/formcms/formcms"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-434", "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-08-28T16:47:04Z",
    "nvd_published_at" : "2025-08-28T15:16:02Z"
  }
}