# CVE-2026-18478: Stored XSS in Magnolia CMS

> An attacker with editor privileges can inject arbitrary HTML and JavaScript into image names, leading to stored XSS execution when images are viewed.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA: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:** No
- **Published:** 10 Aug 2026
- **Updated:** 10 Aug 2026
- **Also known as:** GHSA-jp3f-93v6-xm3f

## What is CVE-2026-18478?

CVE-2026-18478 is a medium-severity cross-site scripting vulnerability in Magnolia CMS, published on 10 Aug 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

Magnolia CMS is vulnerable to Stored XSS in import functionality. An attacker with editor privileges can inject arbitrary HTML and JS into the name of uploaded image, which will be rendered/executed when opening uploaded image.

The issue was fixed in version 6.3.10

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

## Which versions are affected by CVE-2026-18478?


## How do I fix CVE-2026-18478?

No fix has been published for CVE-2026-18478 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-18478 being exploited?

There is no known exploitation of CVE-2026-18478 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-18478 and fix it if it is affected.

What it is: CVE-2026-18478 is a medium-severity cross-site scripting vulnerability in Magnolia CMS, published on 10 Aug 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-2026-18478 in the wild and no public exploit code.

Affected product: Magnolia CMS. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-18478/ (Markdown: https://insights.sbomify.com/CVE-2026-18478/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-18478
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-18478
- OSV: https://osv.dev/vulnerability/CVE-2026-18478

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-18478/
Summaries are generated and may contain mistakes; the official description above is the record.