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Vulnerabilities

Vulnerability · CVE-2026-31834

Umbraco is an ASP.NET CMS.

Published Mar 10, 2026 · catalog updated Jun 17, 2026 · umbraco cms

Check if you run it

No confirmed exploitation is on record for CVE-2026-31834. EPSS is 0.48%. Act only if a listed version of umbraco cms is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.2
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.48%
Remediation
Advisory link
Affected products
cpe umbraco/umbraco cms

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe umbraco/umbraco cmsversion unspecified

How to fix CVE-2026-31834

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-31834. EPSS is 0.48%. Act only if a listed version of umbraco cms is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-269: Improper Privilege Management; CWE-284: Improper Access Control; CWE-862: Missing Authorization. EPSS 0.48%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 10, 2026 · NIST NVD

    Detected

    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

  2. Jun 17, 2026 · NIST NVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-31834

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-31834

    30-day exploitation probability 0.5%

    first.org
  • NIST NVDVulnerability recordCVE-2026-31834

    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 in

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.