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Vulnerability record · CVE-2021-20814 · published 26 August 2021

CVE-2021-20814: Sixapart movable type cross-site scripting vulnerability

SSixapart · Movable Type

Cross-site scripting vulnerability in Setting screen of ContentType Information Widget Plugin of Movable Type (Movable Type 7 r.4903 and earlier (Movable Type 7 Series), Movable Type Advanced 7 r.4903 and earlier (Movable Type Advanced 7 Series), and Movable Type Premium 1.44 and earlier) allows remote attackers to inject arbitrary script or HTML via unspecified vectors.

6.1 CVSS 3.1 Medium EPSS 0.90% · top 41.8% CWE-79 · Cross-site scripting
6.1CVSS 3.1 base score, v2 4.3
0.90%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

Cross-site scripting vulnerability in Setting screen of ContentType Information Widget Plugin of Movable Type (Movable Type 7 r.4903 and earlier (Movable Type 7 Series), Movable Type Advanced 7 r.4903 and earlier (Movable Type Advanced 7 Series), and Movable Type Premium 1.44 and earlier) allows remote attackers to inject arbitrary script or HTML via unspecified vectors.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://jvn.jp/en/jp/JVN97545738/index.html Third Party Advisory
https://movabletype.org/news/2021/08/mt-780-681-released.html Release NotesVendor Advisory
https://jvn.jp/en/jp/JVN97545738/index.html Third Party Advisory
https://movabletype.org/news/2021/08/mt-780-681-released.html Release NotesVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-20814), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.