# CVE-2018-17256: Umbraco CMS vulnerable to stored XSS

> Authenticated users can inject arbitrary web script via the Header Name field in Umbraco CMS, potentially leading to code execution.

- **Severity:** Medium 4.8 (`CVSS:3.0/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 27 Nov 2018
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-wrrj-r2j4-969w

## What is CVE-2018-17256?

CVE-2018-17256 is a medium-severity cross-site scripting vulnerability in Umbraco Umbraco Cms, published on 27 Nov 2018. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

Persistent cross-site scripting (XSS) vulnerability in Umbraco CMS 7.12.3 allows authenticated users to inject arbitrary web script via the Header Name of a content (Blog, Content Page, etc.). The vulnerability is exploited when updating or removing public access of a content.

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

## Which versions are affected by CVE-2018-17256?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `umbraco` | NuGet | All versions to 7.12.3 | None |
| `umbraco` | NuGet | All versions to 7.12.3 | None |

Products: Umbraco Umbraco Cms.

## How do I fix CVE-2018-17256?

No fix has been published for CVE-2018-17256 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-17256 being exploited?

There is no known exploitation of CVE-2018-17256 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-2018-17256 and fix it if it is affected.

What it is: CVE-2018-17256 is a medium-severity cross-site scripting vulnerability in Umbraco Umbraco Cms, published on 27 Nov 2018. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2018-17256 in the wild and no public exploit code.

Affected packages and fixed versions:
- umbraco (NuGet): affected all versions up to 7.12.3; no fix listed
- umbraco (NuGet): affected all versions up to 7.12.3; no fix listed

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-2018-17256/ (Markdown: https://insights.sbomify.com/CVE-2018-17256/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-17256
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-17256
- OSV: https://osv.dev/vulnerability/CVE-2018-17256

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-17256/
Summaries are generated and may contain mistakes; the official description above is the record.