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

> Attackers can bypass configured file extension restrictions in Umbraco CMS to upload malicious files, potentially leading to code execution.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 3 Jun 2025
- **Updated:** 3 Jun 2025
- **Also known as:** GHSA-fr6r-p8hv-x3c4

## What is CVE-2025-48953?

CVE-2025-48953 is a medium-severity vulnerability in Umbraco Umbraco Cms, published on 3 Jun 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-434 (Unrestricted Upload of File with Dangerous Type)

## Which versions are affected by CVE-2025-48953?

2 open source packages ship an affected version, including Umbraco.Cms. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `Umbraco.Cms` | NuGet | From 14.0.0 | 15.4.2 |
| `Umbraco.Cms` | NuGet | From 14.0.0 | 15.4.2 |

Products: Umbraco Umbraco Cms.

## How do I fix CVE-2025-48953?

Upgrade Umbraco.Cms to 15.4.2 or later.

## Is CVE-2025-48953 being exploited?

There is no known exploitation of CVE-2025-48953 in the wild and no public exploit code.

## Other vulnerabilities in Umbraco Umbraco Cms

- [CVE-2025-67288](https://insights.sbomify.com/CVE-2025-67288/): Umbraco CMS has an arbitrary file upload vulnerability (critical 10.0)
- [CVE-2014-10074](https://insights.sbomify.com/CVE-2014-10074/): File upload in n/a (critical 9.8)
- [CVE-2012-1301](https://insights.sbomify.com/CVE-2012-1301/): Server-side request forgery in n/a (critical 9.8)
- [CVE-2012-10054](https://insights.sbomify.com/CVE-2012-10054/): Umbraco CMS < 4.7.1 codeEditorSave.asmx RCE (critical 9.3)
- [CVE-2025-32017](https://insights.sbomify.com/CVE-2025-32017/): Umbraco has a Management API Vulnerability to Path Traversal With Authenticated Users (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-48953 and fix it if it is affected.

What it is: CVE-2025-48953 is a medium-severity vulnerability in Umbraco Umbraco Cms, published on 3 Jun 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2025-48953 in the wild and no public exploit code.

Affected packages and fixed versions:
- Umbraco.Cms (NuGet): affected from 14.0.0; fixed in 15.4.2
- Umbraco.Cms (NuGet): affected from 14.0.0; fixed in 15.4.2

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-48953/ (Markdown: https://insights.sbomify.com/CVE-2025-48953/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-48953
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-48953
- OSV: https://osv.dev/vulnerability/CVE-2025-48953

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-48953/
Summaries are generated and may contain mistakes; the official description above is the record.