What is the CVSS score of CVE-2026-31834?

CVE-2026-31834 has a CVSS 3.1 base score of 7.2 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-31834?

Within 24 hours: Inventory all Umbraco installations and verify version numbers; audit recent user group membership changes in backoffice logs for unauthorized privilege escalation attempts. Within 7 days: Implement network access controls restricting backoffice access to trusted IPs/VPNs; disable or restrict user management permissions for non-essential administrators pending patch availability. Within 30 days: Apply Umbraco security patches (16.5.1 or 17.2.2+) immediately upon release; conduct comprehensive backoffice permission audit and reset any suspicious administrative accounts.

Umbraco CVE-2026-31834

HIGH

Improper Privilege Management (CWE-269)

2026-03-10 security-advisories@github.com

GHSA-rhcg-3h8r-v6vp

Privilege Escalation Umbraco Cms Umbraco

7.2

CVSS 3.1 · GitHub Advisory

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Authenticate to Umbraco backoffice
Delivery

Access user management interface
Exploit

Modify user group memberships
Execution

Assign highly privileged roles
Impact

Escalate privileges to administrator

Vulnerability Assessment

Weakness	CWE CWE-269 OWASP Top 10:2025 A06:2025 - Insecure Design ASVS 5.0 V8 - Authorization Least privilege enforcement MITRE ATT&CK 1 technique across 1 tactic: Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	Authenticated backoffice user with permission to manage users in Umbraco CMS versions 15.3.1 through 16.5.0 or 17.0.0 through 17.2.1. Requires existing backoffice account with user management privileges.
Impact	CVSS 7.2 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: High. User interaction: None. Exploitation requires authentication.
Exploit ScenarioDerived	An attacker (requires authentication) could exploit this vulnerability to compromise the affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Privilege escalation in Umbraco CMS versions 15.3.1 through 16.5.0 and 17.x before 17.2.2 allows authenticated backoffice users with user management permissions to assign themselves elevated privileges by bypassing authorization checks on role assignments. An attacker with these permissions could gain administrative access to the CMS without proper privilege validation. No patch is currently available for affected installations.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:55 CVSS 7.2

Umbraco is an ASP.NET CMS. From 15.3.1 to versions up to 16.5.1 is affected by improper privilege management (CVSS 7.2).

RemediationAI

Fixed in version 16.5.1. Restrict network access to the affected service where possible.

Affected Packages

nuget umbraco.cms fix: 16.5.1, 17.2.2

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in nuget

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability (CWE-269: Improper Privilege Management) affects Umbraco is an ASP.NET CMS. From 15.3.1 to. 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 vulnerabi

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

GitHub Advisory PRIMARY 7.2 HIGH

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

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

CVE Published

Mar 10, 2026 - 22:16 nvd

HIGH 7.2

DescriptionGitHub Advisory

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.

Executive ViewAI

Why It Matters

A privilege escalation vulnerability in Umbraco CMS allows authenticated backoffice users with user management permissions to illegally elevate their own privileges to administrator level, potentially compromising the entire CMS and hosted applications. Organizations running affected Umbraco versions (15.3.1-16.5.0 and 17.0-17.2.1) with multi-user backoffice access face immediate risk of unauthorized administrative control and data compromise.

Business Impact: High

Compensating Controls

Restrict backoffice access via network segmentation and IP whitelisting to trusted administrative networks only; disable or revoke user management/group assignment permissions for all non-critical administrators; implement enhanced logging and real-time alerting on user group membership modifications; consider temporary disabling of backoffice user management features if operationally feasible; conduct daily audits of administrative account activity and group memberships until patch is available.

Threat Intelligence Overview

EPSS Score

0.0%

Top 90% exploitable

Data Quality

5 sources

Confidence: Medium

NVD

CVE.org

EPSS

GitHub

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +36

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Privilege Escalation HIGH

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.