CVE-2026-31834 json
Umbraco Affected by Vertical Privilege Escalation via Missing Authorization Checks
published 7mo ago modified 4mo ago also EUVD-2026-10937 , GHSA-rhcg-3h8r-v6vp
- cvss
- 7.2
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 31%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- nuget Umbraco.Cms 16.5.1, 17.2.2
- umbraco umbraco_cms 16.5.1, 17.2.1
Is CVE-2026-31834 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 7mo ago
Exploit prediction
0.38% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.2 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 7.2 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| nuget | Umbraco.Cms | >=15.3.1, <16.5.1 >=17.0.0, <17.2.2 |
16.5.1 17.2.2 |
Affected products
- umbraco Umbraco-CMS
Classification
References
-
github.com
/umbraco/Umbraco-CMS/security/advisories/GHSA-rhcg-3h8r-v6vp
web, vendor-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-31834
advisory
-
github.com
/umbraco/Umbraco-CMS
package
Sources
- CVE List CVE-2026-31834
- GitHub Advisory GHSA-rhcg-3h8r-v6vp
- NVD CVE-2026-31834
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.