Cross-site scripting vulnerability in Edit Boilerplate screen 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.
Use CWE-79, Sixapart vendor hub and Movable Type product page to widen CVE-2021-20815 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2022-38078, CVE-2021-20837 and CVE-2026-25776 for nearby disclosures in the same product family.