# CVE-2026-46609: Umbraco.Cms: XSS/HTML Injection in Umbraco Backoffice confirmation dialog

> Authenticated users can inject HTML into confirmation dialogs, potentially leading to script execution or account takeover in Umbraco CMS.

- **Severity:** Medium 4.6 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N`)
- **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:** 10 Jun 2026
- **Updated:** 10 Jun 2026
- **Also known as:** GHSA-vr9v-27gg-qgx4

## What is CVE-2026-46609?

CVE-2026-46609 is a medium-severity cross-site scripting vulnerability in Umbraco Umbraco Cms, published on 10 Jun 2026. 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 CMS. From version 14.0.0 to before version 17.4.0, authenticated users are able to inject HTML into an input field, which is rendered in the confirmation dialog without proper output encoding. This issue has been patched in version 17.4.0.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-46609?

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 | 17.4.0 |
| `Umbraco.Cms` | NuGet | From 14.0.0 | 17.4.0 |

Products: Umbraco Umbraco Cms.

## How do I fix CVE-2026-46609?

Upgrade Umbraco.Cms to 17.4.0 or later.

## Is CVE-2026-46609 being exploited?

There is no known exploitation of CVE-2026-46609 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-2026-46609 and fix it if it is affected.

What it is: CVE-2026-46609 is a medium-severity cross-site scripting vulnerability in Umbraco Umbraco Cms, published on 10 Jun 2026. 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-2026-46609 in the wild and no public exploit code.

Affected packages and fixed versions:
- Umbraco.Cms (NuGet): affected from 14.0.0; fixed in 17.4.0
- Umbraco.Cms (NuGet): affected from 14.0.0; fixed in 17.4.0

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-2026-46609/ (Markdown: https://insights.sbomify.com/CVE-2026-46609/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46609
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46609
- OSV: https://osv.dev/vulnerability/CVE-2026-46609

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-46609/
Summaries are generated and may contain mistakes; the official description above is the record.