Is CVE-2021-20810 actively exploited?

No active exploitation of CVE-2021-20810 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-20810 be exploited remotely?

Yes. CVE-2021-20810 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-20810?

CVE-2021-20810 has a CVSS score of 6.1 (MEDIUM).

HOME VULNERABILITIESCVE-2021-20810

MEDIUM

CVE-2021-20810

CWE-79Published: August 26, 2021· Updated: Jun 17, 2026

6.1

CVSS v3.1

Official Description

Cross-site scripting vulnerability in Website Management 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.

NVD Source

Technical Analysis

CVE-2021-20810 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.

From a weakness classification perspective (CWE-79): Cross-site scripting (XSS) vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users.