Vulnerability-Lookup

CVE-2026-31834 (GCVE-0-2026-31834)

Vulnerability from cvelistv5 – Published: 2026-03-10 21:53 – Updated: 2026-03-11 15:58

Title

Umbraco Affected by Vertical Privilege Escalation via Missing Authorization Checks

Summary

Umbraco is an ASP.NET CMS. From 15.3.1 to before 16.5.1 and 17.2.2, A privilege escalation vulnerability has been identified in Umbraco CMS. Under certain conditions, authenticated backoffice users with permission to manage users, may be able to elevate their privileges due to insufficient authorization enforcement when modifying user group memberships. The affected functionality does not properly validate whether a user has sufficient privileges to assign highly privileged roles. This vulnerability is fixed in 16.5.1 and 17.2.2.

Severity ?

7.2 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CWE

CWE-269 - Improper Privilege Management
CWE-284 - Improper Access Control
CWE-862 - Missing Authorization

Assigner

GitHub_M

References

URL

Tags

https://github.com/umbraco/Umbraco-CMS/security/a…

x_refsource_CONFIRM

Impacted products

	Vendor	Product	Version
	umbraco	Umbraco-CMS	Affected: >= 15.3.1, < 16.5.1 Affected: >= 17.0.0, < 17.2.1

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-31834

Vulnerability from fkie_nvd - Published: 2026-03-10 22:16 - Updated: 2026-03-18 19:49

Severity ?

7.2 (High) - CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-rhcg-3h8r-v6vp	Vendor Advisory

Impacted products

	Vendor	Product	Version
	umbraco	umbraco_cms	*
	umbraco	umbraco_cms	*

JSON

To clipboard

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GHSA-RHCG-3H8R-V6VP

Vulnerability from github – Published: 2026-03-11 14:54 – Updated: 2026-03-11 14:54

Summary

Umbraco Affected by Vertical Privilege Escalation via Missing Authorization Checks

Details

Description

A privilege escalation vulnerability has been identified in Umbraco CMS. Under certain conditions, authenticated backoffice users with permission to manage users, may be able to elevate their privileges due to insufficient authorization enforcement when modifying user group memberships.

The affected functionality does not properly validate whether a user has sufficient privileges to assign highly privileged roles.

Impact

An authenticated backoffice user may be able to escalate their privileges to Administrator level.

Successful exploitation results in full administrative control of the affected Umbraco CMS instance, including unrestricted access to content, user management, and configuration settings.

The impact is significantly mitigated by the fact that this can only be exploited by a user that has already been given access to the "Users" section in the CMS. For most Umbraco setups, such users are already also "Administrators".

Patches

The issue is patched in 16.5.1 and 17.2.2.

Workarounds

There is no workaround other than upgrading for setups where they want to have users with permission for the "Users" section without also being content with those users also being part of the "Administrators" user group.

Severity ?

7.2 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "Umbraco.Cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "15.3.1"
            },
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            }
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        }
      ]
    },
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      "package": {
        "ecosystem": "NuGet",
        "name": "Umbraco.Cms"
      },
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        {
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            }
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        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-31834"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-269"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-11T14:54:05Z",
    "nvd_published_at": "2026-03-10T22:16:21Z",
    "severity": "HIGH"
  },
  "details": "### Description\nA privilege escalation vulnerability has been identified in Umbraco CMS. Under certain conditions, authenticated backoffice users with permission to manage users, may be able to elevate their privileges due to insufficient authorization enforcement when modifying user group memberships.\n\nThe affected functionality does not properly validate whether a user has sufficient privileges to assign highly privileged roles.\n\n### Impact\nAn authenticated backoffice user may be able to escalate their privileges to Administrator level.\n\nSuccessful exploitation results in full administrative control of the affected Umbraco CMS instance, including unrestricted access to content, user management, and configuration settings.\n\nThe impact is significantly mitigated by the fact that this can only be exploited by a user that has already been given access to the \"Users\" section in the CMS.  For most Umbraco setups, such users are already also \"Administrators\".\n\n### Patches\nThe issue is patched in 16.5.1 and 17.2.2.\n\n### Workarounds\nThere is no workaround other than upgrading for setups where they want to have users with permission for the \"Users\" section without also being content with those users also being part of the \"Administrators\" user group.",
  "id": "GHSA-rhcg-3h8r-v6vp",
  "modified": "2026-03-11T14:54:05Z",
  "published": "2026-03-11T14:54:05Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-rhcg-3h8r-v6vp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31834"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/umbraco/Umbraco-CMS"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Umbraco Affected by Vertical Privilege Escalation via Missing Authorization Checks"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-31834 (GCVE-0-2026-31834)

FKIE_CVE-2026-31834

GHSA-RHCG-3H8R-V6VP

Description

Impact

Patches

Workarounds

Tags

Sightings

Nomenclature