Umbraco Backoffice API Allows Unauthorized Modification of Domain Data

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-31832: 0.19% estimated exploitation activity in the next 30 days; percentile 8.78 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

11 Mar 2026, 00:24 UTC

Last modified by the source

11 Mar 2026, 05:47 UTC

Source last checked

26 Oct 2026, 17:04 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fpvf-fvp5-996r

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# Patch Next advisory brief: CVE-2026-31832

Advisory: Umbraco Backoffice API Allows Unauthorized Modification of Domain Data
IDs: CVE-2026-31832, GHSA-fpvf-fvp5-996r
Record: https://patchnext.com/advisories/cve-2026-31832 (revision 1, source checked 26 Oct 2026, 17:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: umbraco.cms 17.2.2, 16.5.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet umbraco.cms: affected >= 14.0.0, < 16.5.1; >= 17.0.0, < 17.2.2; fixed in 16.5.1, 17.2.2

## Suggested inspection (read-only)
- NuGet umbraco.cms: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on umbraco.cms.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-fpvf-fvp5-996r (GitHub-reviewed advisory GHSA-fpvf-fvp5-996r lists affected ranges: NuGet umbraco.cms >=14.0.0 =17.0.0 <17.2.2)

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