# CVE-2026-23704: File upload in Movable Type (Cloud Edition)

> Non-admin users can upload malicious files that execute arbitrary scripts in administrators' browsers, affecting EOL Movable Type versions.

- **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: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:** No
- **Published:** 4 Feb 2026
- **Updated:** 4 Feb 2026
- **Also known as:** GHSA-5369-cwvv-7r63

## What is CVE-2026-23704?

CVE-2026-23704 is a medium-severity vulnerability in Six Apart Ltd. Movable Type (Cloud Edition), published on 4 Feb 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

A non-administrative user can upload malicious files. When an administrator or the product accesses that file, an arbitrary script may be executed on the administrator's browser. Note that Movable Type 7 series and 8.4 series, which are End-of-Life (EOL), are affected by the vulnerability as well.

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

## Which versions are affected by CVE-2026-23704?


## How do I fix CVE-2026-23704?

No fix has been published for CVE-2026-23704 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-23704 being exploited?

There is no known exploitation of CVE-2026-23704 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23704 and fix it if it is affected.

What it is: CVE-2026-23704 is a medium-severity vulnerability in Six Apart Ltd. Movable Type (Cloud Edition), published on 4 Feb 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-2026-23704 in the wild and no public exploit code.

Affected product: Six Apart Ltd. Movable Type (Cloud Edition). 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-2026-23704/ (Markdown: https://insights.sbomify.com/CVE-2026-23704/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23704
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23704
- OSV: https://osv.dev/vulnerability/CVE-2026-23704

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23704/
Summaries are generated and may contain mistakes; the official description above is the record.