GHSA-fpvf-fvp5-996r CVE-2026-31832
Umbraco Backoffice API Allows Unauthorized Modification of Domain Data
- Severity
- 5.4 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.19%
- Chance of exploitation in the next 30 days. Higher than 8.75% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-639 Authorization Bypass Through User-Controlled Key
- Fix
16.5.1- Upgrade Umbraco.Cms to this version or later
Description
Description
A broken object-level authorization vulnerability exists in a backoffice API endpoint that allows authenticated users to assign domain-related data to content nodes without proper authorization checks.
The issue is caused by insufficient authorization enforcement on the affected API endpoint, whereby via an API call, domains can be set on content nodes that the editor does not have permission to access (either via user group privileges or start nodes).
Impact
An attacker can modify domain configurations for content nodes they are not permitted to edit. This may result in malicious or unintended routing behaviour, service disruption, and potential disclosure of configuration-related information.
Patches
The issue is patched in 16.5.1 and 17.2.2.
Workarounds
There is no workaround other than upgrading.
Affected versions
NuGet
| Package | Vulnerable | Fixed in |
|---|---|---|
| Umbraco.Cms | >= 14.0.0, < 16.5.1 |
16.5.1 |
| Umbraco.Cms | >= 17.0.0, < 17.2.2 |
17.2.2 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
Umbraco.Cms NuGet → 16.5.1
- dotnet
dotnet add package Umbraco.Cms --version 16.5.1
Severity breakdown
CVSS 3.1 5.4
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- Low
Weakness
CWE-639: Authorization Bypass Through User-Controlled Key
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
How to prevent it
- Architecture and Design: For each and every data access, ensure that the user has sufficient privilege to access the record that is being requested.
- Architecture and Design, Implementation: Make sure that the key that is used in the lookup of a specific user's record is not controllable externally by the user or that any tampering can be detected.
- Architecture and Design: Use encryption in order to make it more difficult to guess other legitimate values of the key or associate a digital signature with the key so that the server can verify that there has been no tampering.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-wr57-hqmp-fgvh Umbraco: Delivery API leaks protected (Public Access) content through Content Picker / Multi-Node Tree Picker expansion | High | Also affects Umbraco.Cms |
| GHSA-vr9v-27gg-qgx4 Umbraco.Cms: XSS/HTML Injection in Umbraco Backoffice confirmation dialog | Medium | Also affects Umbraco.Cms |
| GHSA-2qjj-h6wp-c7h7 Umbraco.Cms: Open Redirect Vulnerability in Surface Controllers | Medium | Also affects Umbraco.Cms |
| GHSA-rhcg-3h8r-v6vp Umbraco Affected by Vertical Privilege Escalation via Missing Authorization Checks | High | Also affects Umbraco.Cms |
| GHSA-vrqc-59mw-qqg7 Umbraco has Stored XSS in UFM Rendering Pipeline via Permissive DOMPurify Attribute Filtering | Medium | Also affects Umbraco.Cms |
| GHSA-54mj-vcvj-q3v5 Umbraco CMS has an arbitrary file upload vulnerability | Critical | Also affects Umbraco.Cms |
| GHSA-hfv2-pf68-m33x Umbraco Vulnerable to Improper File Access and Credential Exposure in Dictionary Import Functionality | Medium | Also affects Umbraco.Cms |
| GHSA-pgvc-6h2p-q4f6 Umbraco CMS disclosure of configured password requirements | Medium | Also affects Umbraco.Cms |
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