CVE-2021-20809: Sixapart Movable Type

Medium severity, CVSS 6.1. EPSS: 0.9% chance of exploitation in the next 30 days.

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.

Affected products

• Sixapart Movable Type: up to and including 1.44; from 6.0, up to and including 6.8.0; from 7.0, before 7.8.0 (fixed in 7.8.0)

Published 2021-08-26. Last modified 2026-06-17.