CVE-2021-20813
Cross-site scripting vulnerability in Edit screen of Content Data of Movable Type (Movable Type 7 r.4903 and earlier (Movable Type 7 Series) and Movable Type Advanced 7 r.4903 and earlier (Movable Type Advanced 7 Series)) allows remote attackers to inject arbitrary script or HTML via unspecified vectors.
Date published : 2021-08-25
https://jvn.jp/en/jp/JVN97545738/index.html
https://movabletype.org/news/2021/08/mt-780-681-released.html