GHSA-RHCG-3H8R-V6VP
Vulnerability from github – Published: 2026-03-11 14:54 – Updated: 2026-03-11 14:54Description
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.
{
"affected": [
{
"package": {
"ecosystem": "NuGet",
"name": "Umbraco.Cms"
},
"ranges": [
{
"events": [
{
"introduced": "15.3.1"
},
{
"fixed": "16.5.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Umbraco.Cms"
},
"ranges": [
{
"events": [
{
"introduced": "17.0.0"
},
{
"fixed": "17.2.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"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.