CVE-2026-24687: Umbraco.Forms Path Traversal Vulnerability

MODERATE
Advisory Identifier: GHSA-hm5p-82g6-m3xh
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CWE-22
Published
Advisory Summary

CVE-2026-24687 is a MODERATE path traversal vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting Umbraco.Forms libraries in the NuGet ecosystem. The issue involves umbraco.forms has path traversal and file enumeration vulnerabilities in linux/mac. Remediation is available by upgrading affected packages to version 16.4.1, 17.1.1.

CVE-2026-24687 at a Glance

CVE Identifier CVE-2026-24687
GHSA Identifier GHSA-hm5p-82g6-m3xh
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected Product Umbraco.Forms
Package Ecosystem NuGet
Published Date
Last Updated

How to Fix CVE-2026-24687

To remediate this vulnerability, upgrade all affected Umbraco.Forms 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.Forms fixed: 16.4.1 
Upgrade Umbraco.Forms to 16.4.1
Umbraco.Forms fixed: 17.1.1 
Upgrade Umbraco.Forms to 17.1.1
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.Forms

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-24687, inspect your project dependencies for Umbraco.Forms:

inspect dependencies for Umbraco.Forms

Analyze the terminal output to locate any version of Umbraco.Forms in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 16.4.1), 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-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), where the product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. In Umbraco.Forms, 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 It's possible for an authenticated backoffice-user to enumerate and traverse paths/files on the systems filesystem and read their contents, on Mac/Linux Umbraco installations using Forms. As Umbraco Cloud runs in a Windows environment, Cloud users aren't affected. ### Patches This issue affects versions 16 and 17 of Umbraco Forms and is patched in 16.4.1 and 17.1.1 ### Workarounds If upgrading is not immediately possible, users can mitigate this vulnerability by: * Configuring a WAF or reverse proxy to block requests containing path traversal sequences (`../`, `..\`) in the `fileName` parameter of the export endpoint * Restricting network access to the Umbraco backoffice to trusted IP ranges * Blocking the `/umbraco/forms/api/v1/export` endpoint entirely if the export feature is not required However, upgrading to the patched version is strongly recommended. ### References Credit to Kevin Joensen from Baldur Security for finding this vulnerability

CVE-2026-24687 Affected Umbraco.Forms Versions

2 component(s)
Fixed Versions:
16.4.117.1.1
Product / Package Ecosystem Affected Versions Fixed Version
Umbraco.Forms
nuget/Umbraco.Forms
NuGet
≥ 16.0.0
< 16.4.1
16.4.1
Umbraco.Forms
nuget/Umbraco.Forms
NuGet
≥ 17.0.0
< 17.1.1
17.1.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/umbraco/Umbraco.Forms.Issues/security/advisories/GHSA-hm5p-82g6-m3xh
NVD — CVE-2026-24687 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-24687
Umbraco.Forms Source Repository REPOSITORY
https://github.com/umbraco/Umbraco.Forms.Issues

Frequently Asked Questions

What is CVE-2026-24687?
CVE-2026-24687 is a security vulnerability in Umbraco.Forms involving Umbraco.Forms has Path Traversal and File Enumeration Vulnerabilities in Linux/Mac under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal').
Which Umbraco.Forms versions are affected?
Affected versions include releases prior to 16.4.1, 17.1.1 across affected packages: Umbraco.Forms.
What version fixes CVE-2026-24687?
Upgrading to 16.4.1, 17.1.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Umbraco.Forms affected?
Yes, Umbraco.Forms is affected in releases prior to 16.4.1, 17.1.1. Upgrade your dependency to 16.4.1, 17.1.1 or later.
What CWE is associated with CVE-2026-24687?
CVE-2026-24687 is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') (The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.).
How can I check NuGet dependencies for CVE-2026-24687?
Run the dependency tree command: 'inspect dependencies for Umbraco.Forms'. 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-hm5p-82g6-m3xh",
  "modified" : "2026-01-30T14:43:18Z",
  "published" : "2026-01-30T14:43:18Z",
  "aliases" : [ "CVE-2026-24687" ],
  "summary" : "Umbraco.Forms has Path Traversal and File Enumeration Vulnerabilities in Linux/Mac",
  "details" : "### Impact\nIt's possible for an authenticated backoffice-user to enumerate and traverse paths/files on the systems filesystem and read their contents, on Mac/Linux Umbraco installations using Forms. As Umbraco Cloud runs in a Windows environment, Cloud users aren't affected. \n\n### Patches\nThis issue affects versions 16 and 17 of Umbraco Forms and is patched in 16.4.1 and 17.1.1\n\n### Workarounds\nIf upgrading is not immediately possible, users can mitigate this vulnerability by:\n* Configuring a WAF or reverse proxy to block requests containing path traversal sequences (`../`, `..\\`) in the `fileName` parameter of the export endpoint\n* Restricting network access to the Umbraco backoffice to trusted IP ranges\n* Blocking the `/umbraco/forms/api/v1/export` endpoint entirely if the export feature is not required\n\nHowever, upgrading to the patched version is strongly recommended.\n\n### References\nCredit to Kevin Joensen from Baldur Security for finding this vulnerability",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Umbraco.Forms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "16.0.0"
      }, {
        "fixed" : "16.4.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Umbraco.Forms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "17.0.0"
      }, {
        "fixed" : "17.1.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/umbraco/Umbraco.Forms.Issues/security/advisories/GHSA-hm5p-82g6-m3xh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-24687"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/umbraco/Umbraco.Forms.Issues"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-30T14:43:18Z",
    "nvd_published_at" : "2026-01-29T20:16:10Z"
  }
}