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Fencer Vulns
medium 5.3

CVE-2023-49278 json

Umbraco CMS brute force exploit can be used to collect valid usernames

published 2023-12-12 2 y ago modified 2026-09-10 1 mo ago also GHSA-7x74-h8cw-qhxq , EUVD-2023-3155

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 43%
public exploits
0
none known

Summary

Umbraco is an ASP.NET content management system (CMS). Starting in version 8.0.0 and prior to versions 8.18.10, 10.8.1, and 12.3.4, a brute force exploit can be used to collect valid usernames. Versions 8.18.10, 10.8.1, and 12.3.4 contain a patch for this issue.

Patch / fix

  • nuget Umbraco.CMS 8.18.10, 10.8.1, 12.3.4
  • umbraco umbraco_cms 8.18.10, 10.8.1, 12.3.4

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.50% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
GitHub 3.1 0.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N

Affected packages

ecosystem package affected fixed in
nuget Umbraco.CMS
>=8.0.0, <8.18.10
>=9.0.0, <10.8.1
>=11.0.0, <12.3.4
8.18.10
10.8.1
12.3.4

Affected products

  • umbraco Umbraco-CMS

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-307 Improper Restriction of Excessive Authentication Attempts

References

Sources

Fencer Vulns 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.