Brute force exploit can be used to collect valid usernames

Exploitation

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

CVSS

not scored

EPSS

• CVE-2023-49278: 0.50% estimated exploitation activity in the next 30 days; percentile 42.93 (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.

Impact A brute force exploit that can be used to collect valid usernames is possible. Explanation of the vulnerability It's a brute force exploit that can be used to collect valid usernames by using the “forgot password” function when trying to log into the Backoffice. If the username/email is known, it is easier to find the corresponding password. If an email address that was already used and registered by a user, is provided as an input, the server internal processing time takes longer. If the email address does not exist in the database of the registered users, the server would respond immediately.

Published by the source

13 Dec 2023, 13:27 UTC

Last modified by the source

12 Jan 2024, 16:27 UTC

Source last checked

26 Oct 2026, 17:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-7x74-h8cw-qhxq

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# Patch Next advisory brief: CVE-2023-49278

Advisory: Brute force exploit can be used to collect valid usernames
IDs: CVE-2023-49278, GHSA-7x74-h8cw-qhxq
Record: https://patchnext.com/advisories/cve-2023-49278 (revision 1, source checked 26 Oct 2026, 17:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: umbraco.cms 12.3.4, 10.8.1, 8.18.10. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet umbraco.cms: affected >= 8.0.0, < 8.18.10; >= 9.0.0, < 10.8.1; >= 11.0.0, < 12.3.4; fixed in 12.3.4, 10.8.1, 8.18.10

## 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-7x74-h8cw-qhxq (GitHub-reviewed advisory GHSA-7x74-h8cw-qhxq lists affected ranges: NuGet umbraco.cms >=8.0.0 =9.0.0 =11.0.0 <12.3.4)

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